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University Information Technology Services (UITS) Shrewsbury Data Center Scheduled Maintenance

UITS - Services - Statuspage.io Alerts -

Sep 22, 16:15 EDT
Scheduled - WHAT: The UITS Infrastructure Team will be conducting scheduled maintenance in the UITS Shrewsbury Data Center.

IMPACT: From 5:00pm on Saturday, September 23, 2017 until 7:00am Sunday, September 24, 2017 the UMass Shared Services (e.g.HR Direct, Finance, Student (BDL) applications, etc.) Production environments will be unavailable due to UITS Shrewsbury Data Center maintenance.

Exploring Thermoelectric Behavior at the Nanoscale

Research Computing - MGHPCC Feed -

by Helen Hill for MGHPCC

Zlatan Aksamija, an Assistant Professor of Electrical and Computer Engineering at the University of Massachusetts Amherst, uses computers at the MGHPCC to carry out nanomolecular materials modeling experiments exploring the thermoelectric behavior of materials for use in energy applications.

Efficient thermoelectric devices are key to our ability to harvest thermal energy from many sources, among them waste heat lost in traditional electricity production and through automobile exhaust.

Two thirds of the energy generated by conventional power stations is lost as waste heat to cooling towers. A similar percentage of the energy locked up in the fuel you put in your car is lost the same way from the exhaust pipe. But what if that wasted heat could be mopped up and converted into usable electricity?

A temperature gradient produces a voltage in a schematic thermoelectric curcuit

Thermoelectric devices can convert heat energy directly into electrical energy without any need for moving parts like turbines, exploiting a temperature gradient across them. If you take a piece of  metal and heat one end while simultaneously cooling the other, the electrons surrounding the atoms at the hot end will have more energy than the equivalent electrons at the cooler end. As a result, the electrons at the hotter end will be jiggling around faster than those at the cooler end so they’ll tend to move towards the cold end faster than the cold electrons will move towards the hot end. Eventually the cold end will become negatively charged and the hot end will become positively charged. This phenomenon, where a temperature difference can create a voltage, is called the thermoelectric effect and was first described as long ago as the 1820’s by a German physicist called Thomas Johann Seebeck.

Simple as that sounds, and long as that has been understood, one big problem is that the voltage produced is absolutely tiny. And unfortunately this can’t be solved simply by connecting lots of pieces of metal together in series as you would to make a bigger battery because the wires used to connect them, which are also made of metal, will themselves produce a voltage but in the wrong direction opposing the voltage in the pieces of metal.

The way scientists have solved this problem is to use a material that can conduct electricity using positively charged particles rather than electrons. Just like the electrons in the metal, the positively charged particles will move away from the hot side, so now if a chain of them is linked together, the voltages will add up along the series allowing generation of a useful amount of power.

Adithya Kommini, a PhD student working in Aksamija’ lab, is trying to do just this by introducing potential barriers that only allow charged particles with high energy to move from one end to the other. The shape and size of the potential barriers control the amount of charge particle filtering improving the voltage created by the thermoelectric effect without affecting the thermal conductivity.

Charge particles encountering potential barriers experience quantum effects that become predominant especially at the nanomolecular scale. Using computer models to explore the character of such nanomolecular systems, Kommini and Aksamija hope that, along with the structure of the potential barrier, a better understanding of the quantum effects that they cause can help to improve the overall thermoelectric efficiency of the material.

“Nanoengineered silicon wires and nanocomposites have been shown experimentally to have tremendous potential as future thermoelectrics due to their high electrical and low thermal conductivity which, combined, yields a very high energy conversion efficiency,” says Aksamija. “Nonetheless, their usefulness hinges on our ability to simulate and predict which combination of material, geometry, and process is most efficient in energy harvesting applications.”

“Past work in this area focused either on electrical or thermal conductivity calculations alone, but because of the strong interdependence of electrical and thermal transport, such decoupled approaches always fell short of a complete understanding of nanoscale thermoelectrics,” Aksamija continues. “Furthermore, far-from-equilibrium configurations like the non-linear Peltier effect (the absorption or release of heat at a junction in which there is an electric current) are useful at low temperatures and in low-dimensional systems, but require advanced simulation that fundamentally couples together charge and thermal transport to capture the non-linear effects.”

Aksamija says, “In order to reap the benefits of nanoengineered semiconductors for energy applications, we must first understand the physics of charge dynamics, dissipation, and heat transfer at the nanoscale. Simulation tools I have developed contain the essential ingredients to unlock the physics of heat transfer in a multitude of complex nanostructures.”

“Improved thermal and thermo-electric simulation tools for devices and materials that are relevant to future advances in nanotechnology enable a detailed understanding of coupling between electron and phonon (charge and thermal) transport, their interdependence, and the impact on the performance of future nanoscale transistors, thermoelectric converters, and sensors,” says Aksamija. “For this reason, simulation tools are well positioned to become the cornerstone of semiconductor material and device research and design, and have the potential for broad impact on a variety of uses and applications. Such large-scale atomistic materials simulations are made possible by the ultra-fast supercomputing hardware of the MGHPCC.”

About the Researchers

Zlatan Aksamija (left) with graduate student Adithya Kommini – image courtey NET Lab, UMass Amherst

Zlatan Aksamija is an assistant professor in the Electrical and Computer Engineering Department at the University of Massachusetts, Amherst. He is interested in semiconductor nanostructures for energy applications, thermoelectric energy conversion; dissipation in nanoscale devices, electro-thermal simulation, nanoscale heat transfer, thermal devices, and computational nanoscience. Aksamija is PI for the NanoEnergy & Thermophysics (NET) Lab.

Adithya Kommini is a PhD student working in the NET Lab. He pesented the poster HPC_day_17 at HPC Day 2017.

Links

Zlatan Aksamija

NanoEnergy & Thermophysics (NET) lab 

Cancer Walk Fundraiser-Financial Services

Shrewsbury Facilities News -

Financial Services will be displaying our raffle basket fundraisers to support the UMass Medicine Cancer Walk.

We have 5 baskets in total that will be displayed at the South Street Kiosk from 9-2, Friday 09/15 & 09/22.

The drawing will be Friday 09/22 at 2:30PM and the winners will be notified by phone or email on that day.

Major Outage - severe performance degradation for majority of UITS supported systems

UITS - Services - Statuspage.io Alerts -

Sep 7, 14:01 EDT
Resolved - Services are fully restored. We will continue to closely monitor the systems.

Sep 7, 13:46 EDT
Identified - Services have been restored for Amherst, Dartmouth, Medical School, Lowell, and UMSO. We will continue to work on the remaining outage to the Boston users.

Sep 7, 13:33 EDT
Investigating - The majority of UITS supported systems are experiencing degraded performance. We are rapidly working on mitigating the issue.

Cuba Travel Warning

Travel - Home - US Passports & International Travel Warnings RSS -

The Department of State warns U.S. citizens to carefully reconsider travel to Cuba due to Hurricane Irma, a Category 5 storm that is projected to impact Cuba.

This storm may bring significant rainfall and wind that may result in life-threatening flooding, flash flooding, mudslides, and storm surge. Disruptions to travel and services are likely throughout the country. On September 6, the Department authorized the voluntary departure of U.S. government employees and their family members due to Hurricane Irma.

Travelers should apprise family and friends in the United States of their whereabouts, and keep in close contact with their tour operator, hotel staff, and local officials for evacuation instructions. Travelers should also protect their travel and identity documents against loss or damage, as the need to replace lost documentation could hamper or delay return to the United States.

For further information:

  • See the National Hurricane Center website for the latest forecasts related to Hurricane Irma.
  • See the State Department's travel website for the Worldwide Caution, Travel Warnings, Travel Alerts, and Cuba Specific Information.
  • Enroll in the Smart Traveler Enrollment Program (STEP) to receive security messages and make it easier to locate you in an emergency. 
  • Contact the U.S. Embassy in Cuba, located at Calzada between L and M Streets, Vedado, Havana, Cuba. U.S. citizens with emergencies may call +(53)(7) 839-4100 during and after office hours. For afterhours emergencies please press “1” to speak with an emergency operator.
  • Call 1-888-407-4747 toll-free in the United States and Canada or 1-202-501-4444 from other countries from 8:00 a.m. to 8:00 p.m. Eastern Standard Time, Monday through Friday (except U.S. federal holidays).
  • Follow us on Twitter and Facebook

The Bahamas Travel Warning

Travel - Home - US Passports & International Travel Warnings RSS -

The Department of State recommends U.S. citizens avoid all travel to The Bahamas and Turks and Caicos Islands due to Hurricane Irma, a category 5 storm.

On September 6, the Department ordered the departure of non-essential U.S. government employees and their family members due to Hurricane Irma.

A Hurricane Warning has been issued for Turks and Caicos and southeastern Bahamas. A Hurricane Watch has been issued for the Central Bahamas. Storm conditions are expected to reach the southern Bahamas by September 7 and Nassau by September 8. U.S. citizens residing and traveling in coastal areas in this region should be alert to flooding.

We recommend U.S. citizens depart The Bahamas and Turks and Caicos Islands if possible and work with commercial air carriers to leave prior to the arrival of the hurricane. Airports will close once conditions deteriorate and safe travel will not be possible, expected sometime on September 8. We recommend those citizens who are unable to depart to shelter in place in a secure location.

Travelers should apprise family and friends in the United States of their whereabouts, and keep in close contact with their tour operator, hotel staff, and local officials for evacuation instructions. Travelers should also protect their travel and identity documents against loss or damage, as the need to replace lost documentation could hamper or delay return to the United States.

For further information:

  • See the State Department's travel website for the Worldwide Caution, Travel Warnings, Travel Alerts, and Bahamas Specific Information.
  • Enroll in the Smart Traveler Enrollment Program (STEP)to receive security messages and make it easier to locate you in an emergency.
  • Contact the U.S. Embassy in The Bahamas, located at 42 Queen Street (across from the British Colonial Hilton Hotel), Nassau; telephone: 242-322-1181; after hours emergency telephone: 242-357-7004; ACS unit fax: 242-356-7174; e-mail: ACSNASSAU@state.gov ; web page: https://bs.usembassy.gov. (Note: The Turks and Caicos U.S. Consular Agency is currently CLOSED. The Turks & Caicos Consular Agency is located at 2 Venture Ct., Grace Bay Suite 102E, Providenciales, Turks and Caicos.)
  • Call 1-888-407-4747 toll-free in the United States and Canada or 1-202-501-4444 from other countries from 8:00 a.m. to 8:00 p.m. Eastern Standard Time, Monday through Friday (except U.S. federal holidays).
  • Follow us on Twitter and Facebook.

Dominican Republic Travel Warning

Travel - Home - US Passports & International Travel Warnings RSS -

The Department of State warns U.S. citizens to carefully reconsider travel to the Dominican Republic due to Hurricane Irma, a category 5 storm projected to impact the Dominican Republic.

This storm may bring significant rainfall and wind that may result in life-threating flooding, flash flooding, mudslides, and storm surge.  Disruptions to travel and services are likely throughout the country, particularly in eastern and northern regions.  On September 5, the Department authorized the voluntary departure of U.S. government employees and their family members due to Hurricane Irma. 

For further information:

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