Our Beloved friend Piumal Gunawardana has passed away today morning (31st August 2007). He was affected by a serious cancer in his throat. He is a final year student of faculty of engineering,
The author of this post is a friend of him, within last eight years.
http://samitharansara.blogspot.com/2007/06/piyumal-gunawardana-current-situation.html
The hybrid stepper motor consists of two pieces of soft iron, as well as an axially magnetized, round rotor. The term hybrid is derived from the fact that the motor is operated under the combined principles of the permanent magnet and variable-reluctance stepper motors.
The stator core structure of a hybrid motor is essentially the same as its VR counterpart. The main difference is that in the VR motor, only one of the two coils of one phase is wound on one pole, while a typical hybrid motor will have coils of two different phases wound on the same pole. The two coils at a pole are wound in a configuration known as a bifilar connection.
The teeth on the rotor provide an even better path which helps guide the magnetic flux to preferred locations in the air gap.
This type provides better performance with respect to step resolution, torque and speed. The hybrid stepper motor combines the best features of both the PM and VR type stepper motors. These facts further increase the detent, holding and dynamic torque characteristics of the motor when compared with both the VR and PM types.
The rotor is magnetized with alternating north and south poles situated in a straight line parallel to the rotor shaft. These magnetized rotor poles provide an increased magnetic flux intensity and because of this the PM motor exhibits improved torque characteristics when compared with the VR type.
A stepper motor is a brush less, synchronous electric motor that can divide a full rotation into a large number of steps, for example, 200 steps. Thus the motor can be turned to a precise angle. There are three major types of stepper motors available in practice.
1. Variable Reluctance Stepper Motors
2. Permanent Magnet Stepper Motors
3. Hybrid Stepper Motors
The stepper motor required a special driving circuit. This is basically done by using an array of power transistors, or switches.
The theory behind stepper motor operation is the magnetic attraction. The stepper rotor will be non coiled rotor. The stator consists with a set of coils and those coils are connected as a set manner. When one set of coils energized the rotor pole will be subject to attract to particular pole and because of that the rotor axis will subject to rotate.
A fault in a power system is defined as a condition which adds a disturbance to the proper operation and the stability of the system. In simple words, a fault is referred to any abnormal condition, which has occurred in a power system, has properly operated prior to the abnormal condition.
A fault may occur due to various reasons such as environmental conditions, such as lighting, storms, etc., improper maintenance of the power system; insulation failures etc. They can cause the system instability. Therefore it is very important to study the faults and get necessary actions to overcome such situations.
It is essential to ensure the protection of the power system because a fault may cause severe damages to the expensive equipments that connected to the system, even life hazards. When in design phase of a power system, the designer should pay his attention to the protection scheme of the system, should implement the system as a system which has high degree of protection. The method of fault analyze by the aid of sequence components, is a great tool to the designer, to calculate the fault level at any point of the system prior to the implementation as well as after. The results of the fault study will be helping the designer to select the correct ratings for the protective devices such as breakers and relays.
The faults in power systems can mainly be classified as Series faults and Parallel faults. This classification is done in a broader sense. Series faults are referred as the faults that occur along the transmission line serially such as conductor aging, breaking etc. Here we consider only the Parallel faults. Parallel faults may subdivide in to two categories as Symmetrical faults and Asymmetrical faults, by the appearance of them to the system.
Assumptions made in the experiment
In order to reduce the complexity and for a trouble-free implementation in the DC network analyzer the following assumptions were made.
The pre-fault bus voltage is 1 p.u.
Fault currents are very much higher than the load currents and therefore the load currents were neglected
Line resistance is smaller compared to the reactance therefore it can be neglected.
The bus voltages kept in nominal values, therefore it is considered as the pre fault bus voltage is 1 in per unit basis. It is a valid assumption to neglect load currents compared with fault currents because fault currents are normally hundreds of times than the load currents. Normally the lines are made of good conductor materials to minimize the losses and voltage drops. So there resistance compared with reactance is very much smaller. Hence the third assumption is also a valid one and it also eases the analysis.
Generally, the majority of faults in power systems are asymmetrical in nature. Single Line to Ground, Line to Line, Double lines to Ground are the possible combinations of faults that can occur within the system. When this type of fault occurs, it gives rise to unsymmetrical currents. Unsymmetrical currents have different magnitudes in the three lines with unequal phase displacement.
The asymmetrical faults can be analyzed using symmetrical component method. This method resolves the unbalanced three phase system in to three systems, which have same phase sequence as the power system, opposite sequence to the power system, and independent in sequence to the power system, which known as positive sequence, negative sequence and zero sequence respectively. (Actually this is a theorem which can apply for any n number of unbalanced vector systems, which states that they can resolve in to n-1 number of balanced systems and an independent system to the source).
By using this theorem, we can derive the sequence networks to the unbalanced system. Then we can change the interconnections between the sequence networks to represent any type of fault that occur within the system.
Facts, which should consider when deriving, sequence networks
The positive and negative sequence impedances of a line are the same and it is the normal impedance of the line. However the zero sequence impedance is much grater than the positive or negative sequence impedance.
The positive sequence impedance of a synchronous generator is equal to the synchronous impedance of the machine. The negative sequence impedance is much less than the positive sequence impedance. The zero sequence impedance is a variable.
Transformers
The positive and negative sequence impedances of a transformer are equal and it is the impedance of the transformer. But the zero sequence impedance depends on the earth connection.
These are the links of most common free pdf creators that available for free, with their Source code.
Copy and paste this links on your browser.
PDF Creator
An excellent pdf printer driver for windows.
http://nchc.dl.sourceforge.net/sourceforge/pdfcreator/PDFCreator-0_9_3_GPLGhostscript.exe
qvPDF
qvPDF is a PDF creator for Windows. It's implemented as printer driver and uses plugins to execute different actions after creating the PDF.
http://nchc.dl.sourceforge.net/sourceforge/qvpdf/qvPDF_v300.45_setup.exe
Some active RFID tags include sensors such as temperature logging to monitor the temperature of perishable goods. Other sensors that have been married with active RFID include humidity, shock/vibration, light, radiation, temperature, and atmospherics like ethylene.
Related Posts
http://www.hitechno.info/2007/06/operation-of-rfid-tag-example.html
http://www.hitechno.info/2007/06/applications-of-rfid-tags.html
Related Posts
http://www.hitechno.info/2007/06/operation-of-rfid-tag-example.html
http://www.hitechno.info/2007/06/applications-of-rfid-tags.html
Most common applications of RFID tags can be summarized as follows.
Related Posts
http://www.hitechno.info/2007/06/operation-of-rfid-tag-example.html
http://www.hitechno.info/2007/06/applications-of-rfid-tags.html
Suppose a man with implanted RFID tag in his body, approaches to a door with a security lock based on RFID. Then following events will occur, between the lock and the tag.
Related Posts
http://www.hitechno.info/2007/06/operation-of-rfid-tag-example.html
http://www.hitechno.info/2007/06/applications-of-rfid-tags.html
http://www.hitechno.info/2007/06/problems-of-rfid-tags.html
http://www.hitechno.info/2007/06/new-trends-in-rfid.html
As the name implies, Radio frequency Identification (RFID) means the process that identifying objects by means of radio waves. A special device is used to identify the object uniquely, and is called as RFID tag or Radio tag. More precisely this is the process of relying on storing and remotely retrieving data using RFID tags. Nowadays this tag become very small and can be implanted to a product, an animal or even to a person for the purpose of identification by means of radio waves.
Commonly available RFID tag has two major parts. One is an integrated circuit for storing and processing information, modulating and demodulating a radio frequency (RF) signal and perhaps other specialized functions. The second is an antenna for receiving and transmitting the signal. RFID increases the speed and accuracy with which inventory can be tracked and managed thereby saving money for the business.
RFID tags come in three general varieties named as passive, semi-passive (also known as battery-assisted), or active.
Passive RFID tags
The practical read distance of a passive tag has the range of 10 cm to few meters, and it depends on the operating radio frequency, the type of antenna, the size of it and the design of RFID. The lack of an onboard power supply means that the device can be quite small: commercially available products exist that can be embedded in a sticker, or under the skin in the case of low frequency RFID tags.
In February 2007 Hitachi Cooperation announced a RFID device measuring 0.05×0.05 mm, and thins enough to be embedded in a sheet of paper. This is named as µ-Chip. Silicon on insulator (SOI) was used to achieve this integration level of the chip. The new chips can store as much data as the older tags, and the data contained on them can be extracted from as far away as a few hundred meters. This chips can wirelessly transmit a 128 bit unique ID and data (encrypted or not), which is embedded to it in manufacturing process.
Active RFID tags
Active type RFID tags have their own internal power source to energize their integrated circuit module and transmit the signals to the tag reader. Active tags have the ability to conduct a session with the reader by using a handshaking technique. Also these types of tags have the ability of transmitting higher signal power levels to the reader because of its onboard power supply. This feature leads to more effective operation rather than passive tags in environments like water, metal (shipping containers, vehicles), or at longer distances. Many active tags have practical ranges of hundreds of meters, and a battery life of 5 to 10 years. Active tags typically have much longer range (approximately 100 m/300 feet) and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver.
Semi-passive tags are similar to active tags as they have their own power source, but the battery is used just to power the microchip and not broadcast a signal. The RF energy is reflected back to the reader like a passive tag.
Related Posts
http://www.hitechno.info/2007/06/operation-of-rfid-tag-example.html
http://www.hitechno.info/2007/06/applications-of-rfid-tags.html
I Received a domain name, www.hitechno.info. I hope to start a tech forum from this domain. I will Inform you the contents and the policies about this. If you are willing to know more information and hope to became an administrator of a forum section, please let me know.
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The analyzing of a real world power system may be a very complex task for an engineer or for the person who moderate the power system, especially in the case of unexpected faulty conditions that may occur by various means including unpredictable natural disasters. This analyzing process should do by the equivalent mathematical models of the equipments that were connected to power system. It is a great ease, if the engineer can model the system with the aid of a software platform to analyze and simulate the behavior of power system at various scenarios and even when building new one or integrate new one to the existing power system.
PSCAD® is a general-purpose time domain simulation tool for studying transient behavior of electrical networks. First developed in 1976, the EMTDC simulation program has been constantly evolving in its scope and capabilities. Users can now harness the power of EMTDC through the user-friendly PSCAD interface on personal computers. This seamlessly integrated visual environment supports all aspects of conducting a simulation including circuit assembly, run-time control, analysis, and reporting. Simply put, PSCAD is the professional's tool for electromagnetic transient simulation.
MATLAB™, framework also contain a library to simulate power systems, but it cannot model, all the scenarios that can happen to the power system, specially the fault conditions. Therefore PSCAD™ evolved as the only professional tool to simulate and design the power systems, nowadays. This Platform has very efficient simulate engine, with a core written by FORTRAN language. EMTDC can simulate not only complex electric networks but also has the capability of modeling complex power electronics, controls and the non-linear network. When run under the PSCAD graphical user interface, the PSCAD/EMTDC combination becomes a powerful means of visualizing the enormous complexity of portions of the electric power system.
Applications of PSCAD
· Distributed generation studies
· Control system design & optimization.
· Protection system validation
· Lightning and impulse studies
· Power transmission design and testing
· Industrial plant planning
· Power electronic circuits design analyzing and simulation
· Analyzing Asymmetrical faults of Large power systems
· Protection relay coordination
· Arc furnace flicker
· Rotating machines
· Transmission system design & performance
· Power quality studies
· Power electronic design
· Electric machine performance
You may remember the email you received regarding the cancer affected engineering undergraduate student Piyumal Gunawardana of University of Moratuwa, Sri Lanka. This email is to inform his current situation to you.
Piyumal underwent his surgery at the Gleneagles hospital, Singapore. It was done by a group of doctors lead by Dr. Andrew H. Sea. This surgery took nearly 14 hours to complete. Major intention of this surgery was to remove the cancer tumor from Piyumal. As a result of the surgery his tongue, voice box, jaws(lower pair) and other areas of his mouth which were affected by the cancer were removed. Then muscles were taken from his chest and right thigh, and were planted to compensate the removed areas in his face. Feeding tube was attached for feeding purposes and another tube for breathing (this was attached to his throat). Piyumal was in the intensive care unit for 3 days and then transferred to a normal ward. After about three weeks he was discharged and was taken back to Sri Lanka.
This surgery cost us about 6 million LKR and earlier we had to spend another 3 million on his chemos which were given prior to the surgery. We also had to spend another 1.8 million LKR at an emergency situation where the doctors had to do a sudden surgery on Piyumal. We received a great support from people in Sri Lanka and abroad. Lot of people had responded our email and they contributed in various ways to help Piyumal and his family. We would like to mention all of those who helped us when we needed a lot of support with our heartiest gratitude.
After spending two weeks at Sri Lanka, he was consulted by a doctor and he recommended to give some more chemos (set of injections) to avoid any spreading of the cancer (if it exist any more). He has now given two cycles of chemos at the Oasis hospital, Colombo. Then a CT scan will be done and Piyumal will have to go back to Singapore for consulting the doctor. We have been able to find the money which was needed up to now with your greatest help. After six months Piyumal will undergo another surgery to make up his face to a normal position (That has not been done in the surgery). At the moment he is fed by the tube. He cannot speak because his tongue and the voice box are removed. Doctors will try to fix them at a later time. At the moment our major intention is to save him from the cancer completely.
Please forward this to all whom you think you should.
Contact details of Piyumal’s family
Telephone : +94412228595
+94602405265
Email : piyumal123@yahoo. com
Thanking you,
Piyumal's family.
I have an article about Late Dr. Amith munindradasa, including his works, his vision and mission. It was published as .pdf, in sinhala language. Those who are willing to receive this article, please send me your e mails, to samitharansara@gmail.com or post your e mail address as a comment to this post. I'll send you the article, as soon as possible.
The Thyristor is a solid state electronic device which had four doped semiconductor layers. The layers were arranged in alternate manner to form a stack shaped structure. Three terminals were taken out from the thyristor, and named as Anode, Cathode and Gate.
Fig 1: Layered Structure of Thyristor and equivalent transistor model
The operation of a thyristor can be described easily, by using the two transistor model, if a current pulse applied to the gate terminal, it triggers the bottom transistor, and because of that, the top one automatically starts to conduct. This caused to keep the gate current until the supply stops or reversed (Anode cathode current). Operation of the thyristor is same as this. It won’t conduct till the gate received a current pulse, after that it will conduct till the removal or reversal of the external source.
Thyristor have three states:
1. Reverse blocking mode - Voltage is applied in the direction that would be blocked by a diode
2. Forward blocking mode - Voltage is applied in the direction that would cause a diode to conduct, but the thyristor has not yet been triggered into conduction
3. Forward conducting mode - The thyristor has been triggered into conduction and will remain conducting until the forward current drops below a threshold value known as the "holding current"
Fig 2: VI Characteristics of the thyristor
In a conventional thyristor, once it has been switched on by the gate terminal, the device remains latched in the on-state (i.e. do not need a continuous supply of gate current to conduct), providing the anode current has exceeded the latching current (IL). As long as the anode remains positively biased, it cannot be switched off until the anode current falls below the holding current (IH). The thyristor can be switched off if the external circuit causes the anode to become negatively biased. In some applications this is done by switching a second thyristor to discharge a capacitor into the cathode of the first thyristor. This method is called forced commutation.
The picotux 100 is the world's smallest Linux computer, only slightly larger (35mm×19mm×19mm) than an RJ45 connector. Inside, there is an ARM7 CPU at 55 MHz running uClinux kernel 2.4.27 and Busybox 1.0. Two communication interfaces are provided, 10/100 Mbit half/full duplex Ethernet and a serial port with up to 230.400 baud. Five additional lines can be used for either general input/output or serial handshaking.
| Technical Data | picotux 100 module |
Processor: | 32-bit ARM 7 Netsilicon NS7520 |
Processor Clock: | 55 MHz |
Flash Memory: | 2 MB |
RAM: | 8 MB SDRAM |
Ethernet: | 10/100 Mbit, HD and FD, auto sensing |
Serial (TTL): | Up to 230.400 bps |
General Input/Output Pins(TTL) | 5, can be used as Handshake |
LED for Ethernet | 2; green (programmable) and yellow (Carrier) |
Supply Voltage: | 3,3 Volt +- 5% |
Supply Current: | 250 mA |
Operating System: | uClinux 2.4.27 Big Endian (native) |
Shell: | Busybox 1.0 and others |
File Systems: | CRAMFS, JFFS2, NFS |
Applications: | Webserver, Telnet |
Size of the Linux Systems in Flash: | 720 KB and more |
Protected Bootloader for Update over Network: | 64 KB Code |
Development System: | GNU Tool chain |
Compiler | GCC 3.4.4 for C/C++ and Fortran |
Binutils | 2.15 |
Library: | uClibc 0.9.26 |
Dimensions: | |
Height: | 19 mm |
Width: | 19 mm |
Deep: | 36 mm |
Package: | Shielded by metal |
Weight: | ca.18 g |
Ambient Temperature: | -40°C to 85°C |
This is the path that you should follow if you wish to participate to Dr. Amith Munindradasa's Funeral.
In Galle road,When you pass Pinwatta Cemetery (Panadura) on sea side, there is a large billboard by Blue Waters Hotel on land side. Passing that, after about 4 by-roads there is left turn (land side) to Pinwatta Pirivena Rd.(some flags are at the road top) Go along that about 1km and you will find a y-junction. Take the right side way and go about 500m further. You will not miss his house, as there is a banner and white flags.
Dr. D Amith Munindradasa, had passed away suddenly in Israel on 12th of June. He was an expert in Power Electronics, Nano Technology, Mechatronics, Quantum Mechanics and also in non technical things such as photography and wildlife.
He was born in Walana, Panadura, Sri lanka in 1966. He has expertise talents in machine mechanics, from his early childhood.
He graduated from University of Moratuwa in 1993 as an Electronic and Telecommunication Engineer, and got his PhD from Liverpool university, in Semiconductor Electronics.
He developed Multi Phase Axial Flux Permanent Magnetic Motor and validate it conceptually via a mathematical model.
As the author of this post, I myself feel very sad, about this coincidence. He was my Electronic Lecturer in University.
May He Attain Nibbana !!
Dear friends,
Dr. Amith Munindradasa has passed away on 11th June 2007 when he was in Israel representing Sri Lanka for a conference. It is reported that he died of pneumonia but it is yet to be confirmed. He was senior lecturer at University of Moratuwa and the former Head of the Department of Electronics and Telecommunication Engineering.
He was graduated in 1993 from University of Moratuwa and was awarded the Doctorate from University of Liverpool. He had an in depth knowledge and taught analogue electronics, quantum electronics, mechatronics and photography for undergraduates and provided proper guidance for students to groom.
Dr. Amith Munindradasa was the president of World University Service (WUS) of University of Moratuwa which provided many services to students at the university. He was a great wildlife admirer and enthusiastic photographer. His knowledge was not limited to academic but widely spread through religious, astrology, astronomy, optics and thermodynamics. His ability to give knowledge to others (teach) was no second to any other; it was clear, precise and more practical. He was a leading researcher in the field of solid state electronics and has contributed an invaluable service for the field of Wildlife in Sri Lanka.
More than he was a great person to get to know who had a true spirit of friendship. He was helpful in every possible way and did his work according to the rule and in a fair manner.
He was considered a great teacher among student and great colleague among staff members and a brilliant advisor among WUS members and a great friend among his nature loving friends and most of all a great contributor for the whole nation of Sri Lanka.
It is our deepest condolences to announce his sudden death; otherwise he could have immensely contributed to the nation in the years to come.
May Dr. Amith Munindradasa attend nibbana!
WUS Committee members
Features
According to the Symantec Security Response Web site, the worm is capable of infecting multiple operating system platforms and is spreading.
The advisory said: "A new worm is being distributed within malicious OpenOffice documents. The worm can infect Windows, Linux, and Mac OS X systems. Be cautious when handling OpenOffice files from unknown sources".
In an interview with ZDNet Australia on Thursday, Dr Jan Hruska, who co-founded rival antivirus firm Sophos and was one of the first ever PC antivirus experts, said that Apple Mac's are not a virus-free platform.
"Viruses on the Mac are here and now. They are available and they are moving around -- it is not as though the Mac is in some miraculous way a virus free environment.
"In terms of numbers, the number of viruses coming out for non-Mac platforms is higher. It gives a false impression that somehow Apple Macs are all virus free," said Hruska.
The worm was first spotted late last month but at the time, it was not thought to be "in the wild".
Once opened the OpenOffice file (badbunny.odg) launches a macro that behaves in several different ways depending on the user’s operating system.
On Windows systems, it drops a file called drop.bad which is moved to the system.ini in the user’s mIRC folder, while executing the Javascript virus badbunny.js that replicates to other files in the folder.
On Apple Mac systems, the worm drops one of two Ruby script viruses in files called badbunny.rb and badbunnya.rb.
On Linux systems, the worm drops both badbunny.py as an XChat script and badbunny.pl as a Perl virus.
Symantec rates the worm "Medium Risk".
Microchip Technology Inc., a leading provider of microcontroller and analog semiconductors, announced that, through its close collaboration with The MathWorks, Inc., a leading developer of technical computing and Model-Based Design software, Microchip's popular MPLAB(R) Integrated Development Environment (IDE) now features a free plug-in for The MathWorks MATLAB(R), Simulink(R) and Real-Time Workshop(R) Embedded Coder modeling and code-generation programs.
MATLAB is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numeric computation. Simulink is a platform for multi-domain simulation and Model-Based Design of dynamic systems. With Simulink, designers can quickly create, model and maintain a detailed block diagram of the system, using a comprehensive set of predefined blocks. MATLAB and Simulink are used by engineers and scientists in industry, government and education.
The MPLAB IDE is a free, feature-rich, integrated toolset for the development of embedded applications employing Microchip's PIC(R) microcontrollers and dsPIC(R) digital signal controllers. The MPLAB IDE runs as a 32-bit application on the Microsoft Windows(R) operation system, is easy to use, and includes a host of free software components for fast application development and super-charged debugging. The MPLAB IDE also serves as a single, unified graphical user interface for additional Microchip and third party software and hardware development tools. MATLAB and Simulink plug-ins debut in the current version of the MPLAB IDE, version 7.51, and enable designers to select Simulink software models, automatically generate source code, and include the files in MPLAB IDE projects for compilation and build, all within the familiar, easy-to-use MPLAB IDE graphical user interface.
"The integration between MATLAB, Simulink and the MPLAB IDE will dramatically increase the productivity of production organizations using Model-Based Design with Microchip's hardware," said Tom Erkkinen, Embedded Applications manager of The MathWorks, Inc. "With push-button automation, engineers can now generate code from their executable specification models, compile it, and download the code to their embedded processor for on-target rapid prototyping or production deployment."
"Wielding the power of MATLAB and Simulink from the MPLAB IDE desktop further empowers the designer of embedded designs using Microchip devices." said Derek Carlson, vice president of Microchip Development Tools. "This collaboration is a significant addition to our tool suite for Microchip's 16-bit microcontrollers, and sets the stage for future cooperative efforts."
Gigabyte GA-965P-DQ6 Overview:
The Platinum range is feature filled, but MSI's most high-end product. Today, we have the P6N SLI Platinum, which is based on Nvidia's nForce 650i SLI chipset. Though the P6N SLI Platinum isn't the top dog in the line-up, it's far from being a no-frills SLI motherboard - MSI has opted to kit this out with a large complement of goodies.
The nForce 650i Ultra boards were expected in February and are still due soon, but considering the low price of the nForce 650i SLI and the recent release of the nForce 680i LT SLI, there’s a question of how little these will cost. This still means the nForce 650i SLI is the bottom end SLI chipset you can buy, but does this mean it skimps on performance as well?
SCSI HAS LONG RULED the enterprise world, but Serial ATA is slowly creeping into corporate server rooms. Serial ATA simply can't be beaten when it comes to storage density, and when you're paying for not only the drives, but also the rack they sit in, density can be an even more important metric than performance.
Today, the highest capacity SCSI drives top out at 300GB—just 60% of the capacity of today's enterprise-class Serial ATA drives, which are available up to 500GB. Seagate has just raised the bar even higher, introducing a new Barracuda ES hard drive with a whopping 750GB of storage. To put that into perspective, consider the storage capacity of a four-drive 1U rack server running RAID 5. With 300GB SCSI drives, you won't even break one terabyte. 500GB Serial ATA drives could give you 1.5TB of redundant capacity, while an array of 750GB Barracuda ES drives would offer a cool 2.25TB, all in the same physical space.
The Barracuda ES owes its freakish capacity to the perpendicular recording technology it shares with Seagate's desktop-oriented Barracuda 7200.10. Physically, the drives are nearly identical. However, the Barracuda ES packs firmware optimizations that promise better performance under more demanding loads, an attribute whose appeal extends beyond the enterprise world and into the enthusiast's realm.
How does the Barracuda ES compare with other enterprise-class Serial ATA hard drives? Is it really any faster than the Barracuda 7200.10? Read on to find out.
What makes an ES?
The Barracuda ES is based on the same drive platters and mechanics as the 7200.10, but it's built to withstand cramped rackmount enclosures where drives can be packed tighter than steerage class on a budget airline. All hard drives vibrate during normal spinning and seek operations, and those vibrations can disrupt the operation of a drive in close proximity by shaking the drive head off its intended path. The disrupted drive must then wait for its head to move back into position before resuming normal operation, resulting in a performance penalty.
To combat vibration-induced performance degradation, the Barracuda ES is outfitted with sensors that detect rotational vibration and adjust the drive head accordingly. These sensors allow the ES to tolerate a rotational vibration of 12.5 rad/second2 with a rotational profile of 20-800Hz. The Barracuda 7200.10, on the other hand, can only tolerate 5.5 rad/second2 between 10 and 300Hz.Apart from the ES's rotational vibration sensors, the drive is physically identical to the Barracuda 7200.10. It uses the same 188GB platters with perpendicular recording and is available with up to 16MB of cache. That cache is programmed a little differently on the ES, of course, but it's the same chip.
In addition to different cache segmentation, the ES's firmware offers a handful of RAID-specific features that you won't find in the Barracuda 7200.10. Among them is Error Recovery Control, which limits the drive's error recovery time to 12 seconds. This prevents prolonged error recovery attempts from causing drives to be prematurely dropped from RAID arrays. Similar functionality is available on Western Digital's enterprise-class Serial ATA drives, although WD recommends disabling the feature for single-drive operation. Error Recovery Control apparently doesn't hinder the Barracuda ES in single-drive systems.
Error recovery is nice, but avoiding errors is even better. To help reduce the number of errors the ES encounters in thermally challenging enterprise environments, the Barracuda ES monitors temperatures and shuffles I/O requests in a manner that allows the drive to cool if it gets too hot. The ES also includes features to simplify multi-drive firmware updates and speed RAID initialization.
Hard drive manufacturers seem loath to publish performance specifications for their desktop hard drives, so it's hard to compare the ES's seek times and sustained transfer rate specs to those of the 7200.10. We'll see how real world seek times and transfer rates shake out when we move to our performance benchmarks.
Google fired another warning shot across the bows of Microsoft yesterday with the launch of software that allows people to use its services even when they are not connected to the internet.
Google Gears will help people to take information from web-based programs and use it offline, enabling them to use services that usually requires a web connection on a computer's hard disk instead.
The system is also being opened up to allow independent developers to create their own products based on the concept.
The announcement will be watched closely by Microsoft, which recently launched its own system, Silverlight, for bridging the gap between the online and offline worlds. The arrival of Gears could be particularly threatening because it is likely to help Google Docs, the company's suite of office software, make a concerted challenge to Microsoft's core office software business.
Docs — which incorporates word processing, spreadsheet and presentation programs — only works with an active internet connection. Allowing it to operate on a computer's hard drive would bring it into competition with the dominant Microsoft Office brand and mark the latest step in Google's slow but inexorable invasion of the Seattle-based software company's territory.
Eric Schmidt, Google's chief executive, said that giving external programmers the ability to develop the system would strengthen its position.
"With Google Gears, we're tackling a key limitation of the browser in order to make it a stronger platform for deploying all types of applications," he said. "We believe strongly in the power of the community to stretch this new technology to the limits of what's possible and ultimately emerge with an open standard that benefits everyone."
The announcement came as Google launched its first international Developer Day, an open house event being held in 10 locations worldwide with more than 5,000 attendees. The concept behind it is to talk to third parties who build software and services based on Google's business, and explain some of the inner workings of its products to them.
By opening up the often-secretive world of Google and encouraging more corporate partners, it believes it can increase its penetration of the web even further. With many web start-ups created on the back of so-called "mash-ups" — hybrids that mix different online services together to create a new concept — larger technology organisations have found that third parties are even more reliant on them.
"This is a complete shift from the portal strategy of the 1990s," said Jeff Huber, Google's vice president of engineering. "Back then everyone was in it for themselves, there was no integrating with rivals and you were only working for yourself. Now we are thinking about our products as building blocks. It's a virtuous cycle."
Google is just one of a number of companies investing heavily in these concepts, with rivals such as Yahoo!, Microsoft and Amazon also following suit. Many are particularly keen to contribute to the open-source community, which develops software and tools that can be used freely by anybody at no cost. Alexandra Palace in London will play host to a "Hackday" event this month being held jointly by Yahoo! and the BBC intended to foster relations with the technical community.
"I think that all these events are part of a conversation that has to happen between companies like the BBC and everyone else," said Matthew Cashmore, development producer at the BBC. He stressed that it was important for many people to be able to talk to each other face to face and get a feeling for the internet industry outside of Silicon Valley. "It has to be very social; you can't exist solely on the web, you have to be out there rubbing shoulders with each other. It's important in this industry that it's not all just about west coast America."
VIA EPIA 'Mini ITX' compact SBC (Single Board Computer)
Commell LV-675 -- [Dec. 14, 2005] -- Claimed to be the first mini-ITX board to support Pentium M and Celeron M processors with a 533 MHz front side bus (FSB), the LV-675 comes with drivers for embedded Linux.
Kontron 886LCD-M/mITX(BGA) -- [Nov. 2, 2005] -- A passively cooled, Linux-ready mini-ITX motherboard with a soldered-down BGA (ball-grid array) Intel processor and long-term availability, the 886LCD-M/mITX(BGA) has a 600MHz mobile Celeron processor, and targets cost-sensitive, low-power applications, such as POS (point-of-sales/service), gaming, banking, measurement, medical, and industrial computing.
Kontron 786LCD/mITX -- [Sep. 28, 2005] -- A mini-ITX board targeting cost-constrained, high-volume applications such as gaming, POS (point-of-sales/service), data communications, and medical equipment, the 786LCD/mITX is based on a mature Intel chipset yet supports USB 2.0, SATA, FireWire, and LVDS, Kontron says.
Arbor Technology ITX-i7435 -- [Sep. 27, 2005] -- A mini-ITX motherboard graced with a PCI Express x16 slot, and targeting multimedia, gaming, and other applications requiring high-quality graphics performance, the ITX-i7435 supports several Socket 478 Pentium M/Celeron M processors.
Kontron 886LCD/mITX -- [Aug. 28, 2005] -- A highly integrated mini-ITX motherboard with Pentium 4 and Celeron processor options up to 3 GHz, the 886LCD/mITX includes an AGP/DVO slot and targets CPU-intensive, cost-sensitive industrial applications.
Axiomtek SBC86800 board and EM603201 case -- [Jul. 7, 2005] -- A mini-ITX board supporting Intel Pentium-4 and Celeron processors, and available with a rolled steel micro-box with 180-Watt ATX power supply.
iBase MB720 -- [Apr. 29, 2005] -- A Via-based mini-ITX board that uses the same chipset used in newer Via mini-ITX boards, the MB720 is available with an LVDS module supporting 4:3 and 16:9 LCD displays. It targets industrial, gaming, medical, digital entertainment and other applications requiring stable and long lifecycle platforms.
Via ships dual-processor mini-ITX board -- [Mar. 11, 2005] -- Via is now sampling its first dual-processor mini-ITX board. The DP-310 features dual 1GHz Eden-N processors, along with gigabit Ethernet, SATA, a media-processing graphics system, and more. It targets high-density server systems, appliance servers, and compact embedded digital devices.
World's fastest Mini-ITX mobo? -- [Feb. 18, 2005] -- Powered by Pentium M processors at up to 2.3 GHz, the P620 Hawk is crammed with interfaces and expansion buses, and may also be the first Mini-ITX mobo to offer PMC expansion.
Coventive Uranus -- [Jan 4, 2005] -- A mini-ITX SBC (single-board computer) targeting Linux-based DVRs (digital video recorders), wireless TVs, network MPEG encoding boxes, and surveillance systems. The Uranus board is based on a MIP64 Toshiba SoC (system-on-chip), along with a Vweb MPEG coprocessor, and comes with a Linux SDK (software development kit).
Commell LV-667 -- [Dec. 17, 2004] -- Commell is shipping a mini-ITX board said to offer advanced graphics features, based on Via's latest northbridge. The LV-667 is available with a variety of video port options, and targets PVRs, set-top boxes, gaming machines, kiosks, POS (point-of-sales/service) devices, and more.
Toshiba mini-ITX-based PVR ref design -- [Oct. 18, 2004] -- Toshiba America Electronic Components (TAEC) has released a hardware/software reference design targeting digital multimedia appliances with sub-$100 BOMs (bills-of-material). The reference design, designated AVM49R, includes a mini-ITX board with a dedicated MPEG-1/2/4 codec chip alongside a 333MHz MIPS RISC-based SoC.
VIA dual-processor (DP) mini-ITX board -- Oct. 6, 2004 -- Via expects to ship its long-awaited "SP" mini-ITX board in November, followed in early 2005 by a "DP" model with dual nanoBGA embedded processors -- quite likely the world's first dual processor mini-ITX mobo. Both mini-ITX boards will feature a new northbridge supporting faster FSB (front-side bus), southbridge interconnect, and DDR memory speeds, and hardware MPEG-4 acceleration.
New VIA mini-ITX board targets vertically challenged apps -- June 24, 2004 -- VIA is shipping an ultra-low profile mini-ITX mainboard suitable for Linux-based flat TVs, LCD-panel computers, and other vertically challenged devices. The Epia MS uses a minimalistic I/O backplate and SODIMM memory for a slimmer form-factor, and is VIA's first mini-ITX board available with a fanless 1GHz Eden embedded processor.
Next-gen VIA mobo touts speed, security, MPEG-4 -- May 27, 2004 -- VIA will preview its next-generation mini-ITX board for the consumer electronics market at next week's Computex 2004 in Taipei. The EPIA SP features a new graphics and memory controller hub (GMCH) supporting faster front-side bus (FSB), memory, and southbridge interconnect speeds. It also features a C3 processor clocked at 1.3GHz, integrated PadLock Hardware Security Suite, and MPEG-4 acceleration. 
Mini-ITX board boasts die-shrunk Pentium M -- May 25, 2004 -- Single-board computer vendor Lippert announced mini-ITX form-factor board support for Intel's new Dothan processor, a 90nm die-shrink of the Pentium M released today by Intel. The Dothan chip includes 170 million transistors, compared with 77 million on the previous Pentium M, making lots more room for on-chip memory caches, according to Lippert.
Centrino-like mini-ITX board available passively cooled -- Jan. 17, 2004 -- German single-board computer vendor Lippert is shipping a passively cooled version of its Centrino-like Thunderbird mini-ITX board based on an Intel Pentium M running at 1.3GHz. An actively cooled version running at 1.6GHz has been available since mid-December, 2003. Additionally, Lippert is readying a number of mini-PCI expansion devices and PCI riser cards for the boards. 
Transmeta spins Crusoe-based mini-ITX mobo -- Jan. 07, 2004 -- Transmeta introduces two reference platforms to support device and system designs based on its Efficeon TM8600 and Crusoe TM5900 processors. Both platforms support Linux. Interestingly, the Crusoe TM5900 reference platform (pictured on the left) is implemented in the increasingly popular mini-ITX motherboard form-factor. 
Mini-ITX P4M motherboard soars to 1700MHz and beyond -- Dec. 17, 2003 -- Taiwanese industrial computer board supplier Commell pushes the speed envelope for the compact mini-ITX mini motherboard form-factor, with the release of a mini-ITX board that supports Intel's mobile Pentium 4 processors at clock rates in excess of 1.7GHz.
Computing Client Development Center of Beijing launches low-end mini-ITX board for thin clients -- Dec. 11, 2003 -- The GSTB-3602 mini-ITX board and reference design kit is the very first product from Computing Client Development Center of Beijing, a joint venture between Advanced Micro Devices (AMD) and BLX IC Design Corp. Ltd.First Pentium M based mini-ITX SBC runs Linux Sep. 03, 2003 -- Lippert GmbH introduces what is claimed to be the first mini-ITX form-factor motherboard to be based on an Intel Pentium M processor. The compact (6.7 x 6.7 in.) Thunderbird SBC features a Centrino-like architecture, with Intel northbridge and southbridge and a mini-PCI slot, and runs Linux, the company says.
2W ARM9-based mini-ITX board comes with Debian Linux -- Oct. 29, 2003 -- Simtec Electronics launches a mini-ITX based evaluation board that, in the highest specification of several available configurations, draws just 2 watts. The Simtec Samsung 2410 evaluation board is based on a Samsung S3C2410 ARM9 processor and is supplied with a Linux kernel, Debian cross-development environment, and several sample applications.
First mobile Pentium 4 mini-ITX SBC? -- Jun. 16, 2003 -- Commell announces what is claimed to be the first mini-ITX form-factor single-board computer (SBC) to be based on an Intel mobile Pentium 4 processor. Commell said its LV-670M SBC supports Linux and other embedded and desktop operating systems and targets VoD (video on demand), DVR (Digital Video Recorder), digital video broadcasting (DVB), streaming, surveillance, compression (MPEG), interactive servers, POS, Kiosk, ATM, Panel PC, transaction workstation, and terminal applications. 
The joy of mini-ITX . . . -- Jun. 12, 2003 -- The Globe and Mail's "Chic Geek" Ian Johnson has discovered the mini-ITX motherboard form-factor, and he likes what he sees. In his article titled "Mini-ITX: Incredibly Tiny, eXceptionally cool," Johnson notes that "Mini-ITX motherboards are just starting to go mainstream, and they're real beauties if you want to save money and space. They're about the size of a CD jewel case and sell for between $75 and $200 (U.S.), depending on the speed of their built-in processor. All you have to do is add a case, memory and a hard disk, load an operating system and plug in a monitor, and you're off . . . "
