Friday, January 6, 2012

Stop Spending Time on Job Boards and Pick Up the Phone to Find a New Job [Jobs]

Stop Spending Time on Job Boards and Pick Up the Phone to Find a New Job The old adage "It's not what you know but who you know" often rings true, especially when it comes to job hunting. Even if you have an impressive resume with great credentials, most companies do their hiring based on referrals and suggestions from current employees?or at least those referrals get interviews. All that said, if your job search has you spending day after day behind a screen sending out waves of emailed resumes and automated job applications, it's time to change course and start calling your network instead.

No one's saying you should give up on job search sites and tools, and no one's saying you shouldn't send in your resume to opportunities you find on the web, but according to Career Sherpa, Hannah Morgan points out that you're better off spending more of your time calling your friends and family, past supervisors, colleagues, vendors, and even customers you can still connect with, and other people in your professional network and let them know you're looking for new opportunities and willing to talk to people they can send your way.

If your goals for the new year involve searching for a new job or career, paying more attention to your professional network as opposed to job search sites may be a good way to jumpstart the search. Are you looking for a new job this year? Share your job search tips in the comments below.

Photo by Sh4rp_i.

Job Seekers: Change How You Look for Work | Career Sherpa

Source: http://feeds.gawker.com/~r/lifehacker/full/~3/QXZ-fAQlHSU/stop-spending-time-on-job-boards-and-pick-up-the-phone-to-find-a-new-job

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Thursday, January 5, 2012

Secret, word-of-mouth destinations worth the hunt

Julien Hausherr / HiP Paris Blog

In 2007, American ex-pats and avid cooks Laura Adrian and Braden Perkins began hosting private dinner parties as a way to make new friends in Paris. Several years later, the couple opened Verjus, a restaurant near the Jardin du Palais Royal.

By Marnie Hanel, Departures.com

Several years ago, a house guest visiting me in New York said, ?You?ve taken me to four bars and two restaurants, and none of them have been marked. What is going on??

It was the height of Manhattan?s speakeasy craze, and although it may have gotten ??and may still be ??a little out of hand, there was something irresistible about exploring an underground New York just for New Yorkers.

Slideshow: Hard-to-find travel destinations

In a city that sees 48.8 million visitors each year, the best way to claim a corner of one?s own may be to hide it behind a secret phone booth, underneath a pizza stand, beyond the kitchen, on the other side of the wine cellar or in a train car.

The same is true in other cities, of course, which is why digging for insider tips and word-of-mouth directions before a trip always pays off. The legwork is far more fun when the results are guaranteed.

Take, for example, La Petite Cuisine a Paris. British ex-pat Rachel Khoo moved to town to train at the Cordon Bleu, and she ran this two-seat restaurant out of her 256-square-foot apartment. She served lunch just two days each week, on Wednesday and Saturday. Guests were treated to souffl?, ragout or coq au vin, depending on the chef?s inclination.

Khoo is closing her kitchen soon, so here are ten other word-of-mouth addresses worth investigating.

Whether this list leads you to a hilltop spa in Mexico, a helicopter-access-only slope in the Canadian Rockies or a kitchen filled with Italian grandmas hell-bent on perfecting your pesto is up to you. When you?ve arrived, you?ll know you?re there.?

More from Departures.com

Source: http://itineraries.msnbc.msn.com/_news/2011/12/23/9663097-secret-word-of-mouth-destinations-worth-the-hunt

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Red's Scarlet-X 4K camera gets video review: you've never needed $11,700 so badly

Native 4K recording? Check. A built-for-war body? You bet. Backordered despite a downright shocking $11,700 price tag? Most certainly. As with Red's prior products, the Scarlet-X seems to be wowing just about every shooter lucky enough to come into contact with one. Luck for you, the folks over at Cinema5D have spent an inordinate of amount of time with this beast in order to deliver the full skinny on whether it's worth the price (and wait). We won't bother spoiling any conclusions for you, but if you've been toying with the idea of blowing your (and your SO's) bonus on one of these in a bid to start your own movie house, there's a vid just after the break that deserves your attention.

Continue reading Red's Scarlet-X 4K camera gets video review: you've never needed $11,700 so badly

Red's Scarlet-X 4K camera gets video review: you've never needed $11,700 so badly originally appeared on Engadget on Mon, 02 Jan 2012 20:08:00 EDT. Please see our terms for use of feeds.

Permalink   |  sourceCinema5D, Red  | Email this | Comments


Source: http://feeds.engadget.com/~r/weblogsinc/engadget/~3/4p21_hJ7qhg/

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Wednesday, January 4, 2012

Research finds trigger for breast cancer spread

Tuesday, January 3, 2012

Research led by Shyamal Desai, PhD, Assistant Professor of Biochemistry and Molecular Biology at LSU Health Sciences Center New Orleans, has discovered a key change in the body's defense system that increases the potential for breast cancer to spread to other parts of the body. The results, reported for the first time, are featured in the January 2012 issue of Experimental Biology and Medicine.

For cancer cells shape matters. All cells contain a protein cytoskeleton that acts as a scaffold determining overall shape and function, the position of the cell within an organ or tissue, and the ability of the cell to communicate with its neighbors to prevent the uncontrolled growth typical of cancer cells. However, cell transformations that result in cancer disrupt the genetic programs of the cell and alter the cytoskeleton, leading to changes in shape, function, and cell communication that produce uncontrolled growth and metastatic spreading of the tumor. Understanding these changes to the normal genetic program of a cell and the consequences that ultimately lead to cancer have been major challenges to cancer biologists.

This research, funded by the National Institutes of Health, found that a cellular defense system called the ISG15 pathway, which is normally involved in fighting bacterial and viral infection, is triggered in breast cancer to disrupt normal cytoskeletal function and increase the possibility that the cancer cells will metastasize, or spread.

"Our findings, for the first time, causally link an alteration in the ISG15 pathway during transformation with metastatic potential," notes Dr. Shyamal Desai, Assistant Professor of Biochemistry and Molecular Biology at LSU Health Sciences Center New Orleans, "thus providing a novel therapeutic target for future drug discovery."

Cells contain a protein quality control pathway termed the Proteasome that breaks down damaged and unneeded proteins to their component amino acids for recycling. Such proteins are marked for degradation by flagging them with a small protein called Ubiquitin, which is then recognized by the Proteasome. Alterations in the genetic program that controls the Ubiquitin/Proteasome system have been known for some time to cause cell transformation and cancer. More recently, Dr. Desai and her colleagues have demonstrated that, unlike normal cells, transformed cancer cells produce increased amounts of a related control system that marks proteins with another small protein called ISG15.

Previous research reports that the amount of ISG15 is increased in high-grade compared with low-grade cancers. The ISG15 system is normally activated by interferon and is part of an ancient cellular immune response designed to counter bacterial and viral infection. By a still unidentified mechanism, cancer cell transformation activates the ISG15 pathway. Dr. Desai and colleagues have previously reported that activation of the ISG15 system interferes with function of the Ubiquitin/Proteasome pathway. In their latest work, Dr. Desai and colleagues show that several key proteins that regulate cell movement, invasion, and metastasis are blocked from Proteasome degradation by the ISG15 system and that genetic manipulation to inhibit this pathway reverses cancer cell transformation, suggesting an approach to blocking cancer progression.

Arthur Haas, PhD, the Roland Coulson Professor and Chairman of Biochemistry and Molecular Biology at LSU Health Sciences Center New Orleans, discovered the ISG15 pathway and co-discovered the Ubiquitin/Proteasome system that was awarded the 2004 Nobel Prize in Chemistry. "These results provide a functional link between the Ubiquitin and ISG15 pathways that reveals how small cell alterations can yield large overall consequences for cell transformation."

The research team also included Arthur Haas, PhD, and Dr. Desai's lab members Ryan Reed, Surendran Sankar, PhD, and Julian Burks in the LSUHSC Department of Biochemistry and Molecular Biology, Jerome Breslin, PhD, in the LSUHSC Department of Physiology, and Ashok Pullikuth, PhD, in the LSUHSC Department Pharmacology, as well as scientists at the UMDNJ-Robert Wood Johnson Medical School in New Jersey, and the University of Pennsylvania School of Medicine in Philadelphia.

"Although this current project focused on breast cancer, ISG15 is also elevated in a variety of cancers," concludes Dr. Desai. "Therefore, this discovery has important implications in other cancers as well."

###

Louisiana State University Health Sciences Center: http://www.lsuhsc.edu/

Thanks to Louisiana State University Health Sciences Center for this article.

This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.

This press release has been viewed 72 time(s).

Source: http://www.labspaces.net/116383/Research_finds_trigger_for_breast_cancer_spread

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Tuesday, January 3, 2012

NYT: Signs point to tepid consumer spending for 2012

American consumers are running out of tricks.

As the weak economy has trudged on, they have leaned on credit cards to pay for holiday gifts, many bought at discounts. They are dipping into savings to cover spikes in gas, food and rent. They are substituting domestic vacations for international trips, squeezing more life out of their washing machines and refrigerators and switching to alternatives as meat prices have risen.

That leaves little room for a big increase in spending in 2012, economists say, a shaky foundation for the most important pillar of the American economy.

?The consumer is far from healthy,? said Steve Blitz, senior economist for ITG Investment Research.

Even the seemingly robust holiday shopping season is raising concern. After a strong start on Thanksgiving weekend, a pronounced lull followed, causing retailers to mark down products heavily in the week before Christmas. While final numbers for the season are not in, analysts say they are worried that retailers had to eat into profits to generate high revenues.

Consumer spending makes up 70 percent of the economy, so until it ignites, general growth is likely to be sluggish.

Story: New year, new week on Wall Street, same issues

Incomes flat
Macroeconomic Advisers, a forecasting company, projects growth of around 2 percent for the first half of this year, down from an estimate of 3.6 percent in the fourth quarter of 2011 and just 1.8 percent in the third quarter.

For consumers, the reasons for the sluggishness are clear: incomes are essentially flat, job growth is modest, and more than 40 percent of the new jobs in the last two years have been in low-paying sectors like retail and hospitality.

While consumer spending is not ?going to collapse,? said Joel Prakken, senior managing director at Macroeconomic Advisers, ?there are some headwinds there.?

Sarah M. Manley, a marketing consultant with two young sons in Waconia, Minn., has developed coping strategies in the last few years. Laid off in 2008, she started a business. She and her husband can make their mortgage payments and are paying off debts from when a storm damaged their roof.

?It?s not necessarily that I?m saving more money, but I?m paying off some of the debts that were amassed during the last three years, just trying to make headway,? Ms. Manley said.

To do that, she has changed habits. She uses the app GasBuddy to check prices at nearby stations before she buys gas for her car. She buys seasonal food on sale and freezes it ? for Valentine?s Day, she plans to prepare crab legs she bought and froze last summer ? and she is stocking up on holiday hams. She has switched from buying milk in gallon containers to buying it for less in plastic bags from the local gas station.

For big purchases, like the laptop she bought last summer, Ms. Manley still relies on credit, but is careful. She opens credit card accounts offering an introductory rate of no interest, then closes them just before the annual percentage rate kicks in.

?Everybody?s learned how to be frugal in the last two or three years,? she said.

Housing prices still falling
Economic indicators suggest that, while things may not get worse for consumers this year, they will not get much better. In the third quarter of 2011, the most recent period for which figures are available, consumer spending rose slightly more than 1 percent, according to the Commerce Department.

Although housing sales have recently shown signs of recovery, prices are still falling and mortgage lenders are cautious. In November, contracts represented by 33 percent of members of the National Association of Realtors did not close, up from just 9 percent a year ago.

And with more than one in every five borrowers still owing more than their homes are worth, many homeowners feel too pressed to spend on much more than the essentials.

Story: Home prices drop for 2nd straight month, survey shows

The stock market did not help consumers, either. Because of turmoil in the markets in the late summer and early fall, household wealth declined by $2.4 trillion in that period, a contraction likely to make people think twice about big purchases.

Adding to the uncertainty, financial weakness in Europe, and the potential expiration of the payroll tax cut and unemployment insurance benefits in two months, could further soften spending.

?I used to say people will always beg, borrow or steal to spend,? said Allen Sinai, chief global economist at Decision Economics, a consulting firm. He has changed his mind. He is forecasting ?firmer? spending in 2012, but said the economy would ?not grow anywhere near our growth in previous postrecession periods.?

Some signs suggest borrower distress. Credit card delinquencies increased for the first time in almost two years in the third quarter, according to credit bureau TransUnion, though the delinquency rates are still very low. And mortgage delinquencies were about 6 percent at the end of 2011, down a little from a year ago but higher than earlier last year, compared with the prerecession rate of 1.5 to 2 percent.

?That?s a long way to go to get us back to a steady state,? said Steve Chaouki, group vice president for financial services for TransUnion.

Still repaying debt from boom times
Another crucial factor holding back the American consumer is that many people who borrowed heavily during the boom to buy cars or appliances, or take vacations, are still repaying debt and cannot win approval for new loans, so they must find other ways to pay for things.

Though shopping has remained relatively strong, the level of consumer debt in October was at its highest in two years, meaning people are buying on credit rather than with income. And the savings rate in November was 3.5 percent, the lowest since 2007, which suggests shoppers are also buying with savings.

?We don?t think this is sustainable and expect slowing spending growth going forward,? Colin McGranahan, an analyst at Sanford C. Bernstein, wrote in a note to clients that reviewed numbers for November.

In Copley, Ohio, a suburb of Akron, Lynette Paudel, 39, said that some things are looking up: her husband, Govind, received a raise in September when he was recruited to a mechanical engineering job in Akron at a French company.

But she said she was likely to use that extra income to establish a cushion in their savings account and pay off credit card balances. She said it would also ease the strain of sending money to her husband?s family in Nepal each month.

?I know we?re lucky,? said Ms. Paudel, a high school English teacher who said neither she nor her husband lost their jobs in the downturn or its aftermath. But, she said, ?we?re naturally fairly frugal? and plan to remain that way. She said the family will camp during summer vacation and will not replace her 2003 minivan ?until it breaks.?

Even some growth areas in the economy can be explained by tapped-out consumers. Take auto sales, which rose about 10 percent nationwide in 2011 from a year earlier.

?People can only hold onto their cars for so long,? said Romolo Debottis, new-car sales manager at Mike Bass Ford in Sheffield Village, a suburb of Cleveland. He said sales at the dealership should increase this year to 2007 levels, the prerecession peak. ?A lot of them have done that above and beyond what they normally would, and they?re just ready to spend money and buy a new vehicle.?

This story, "For 2012, signs point to retreat in consumer spending," first appeared in the New York Times.

Copyright ? 2012 The New York Times

Source: http://www.msnbc.msn.com/id/45852507/ns/business-us_business/

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Colo. driver killed by branch steered car to safety

BOULDER, Colo. (AP) - A Colorado man who was killed when a 3-foot tree branch flew through his windshield and impaled him in the chest was able to steer the car to safety before losing consciousness.

The wife of 61-year-old James Baker-Jarvis told the Daily Camera that her husband was able to pull the Subaru Outback over to the roadside, saving her from any injury. Baker-Jarvis died later at a hospital.

Saturday's incident north of Boulder came as high winds swept through the Northern Rockies, toppling two semis, forcing shutdowns along long stretches of highways and causing some 19,000 power failures throughout Colorado.

In Wyoming, two people were injured Saturday when debris blew off the roof of a Cheyenne Sam's Club store. The Wyoming Tribune Eagle reports that at least five other people were treated at Cheyenne Regional Medical Center for wind-related injuries.

None of the Wyoming injuries was considered life-threatening. The winds reached gusts of 76 mph in Cheyenne, said Tim Trudel, a forecaster for the National Weather Service.

Cheyenne Fire and Rescue Battalion Cmdr. Pat Hobby responded to the scene and said cars in the parking lot were also damaged by the blowing debris.

"That wind can be dangerous," he said. "When you start getting that high wind, (it) just wears and tears on everything."

In Fort Collins, Colo., wind toppled a large light pole at Hughes Stadium, home of the Colorado State University football team. The Coloradoan reports that the pole crashed onto the upper press box level and slid down into stadium seating. There were no injuries and no immediate damage estimate.

Baker-Jarvis was a theoretical physicist at the National Institute of Standards and Technology. His wife said that he had hoped to one day bicycle across America.

"He loved to be outside," Karen Baker-Jarvis said.

? 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Source: http://www.msnbc.msn.com/id/45840956/ns/weather/

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Monday, January 2, 2012

Effervescent atomization spray: Understanding the modeling process

Effervescent atomization spray: Understanding the modeling process [ Back to EurekAlert! ] Public release date: 1-Jan-2012
[ | E-mail | Share Share ]

Contact: Lin Jianzhong
mecjzlin@public.zju.edu.cn
86-571-868-36009
Science in China Press

Understanding the atomization spray process is not only of academic interest but is also important to various industry applications such as combustion, coating, and chemical synthesis. Significant experimental investigations concerning spray behavior have been conducted in the past. Fundamental understanding of the spray process is, however, still lacking and lags behind applications due to the high complexity of its stochastic behavior. Prof. LIN Jianzhong and his group proposed a comprehensive three-dimensional model to predict the droplet mean size and other spray characteristics by describing both primary and secondary atomization. Recently, they reviewed the theories, practical modeling treatments and the main achievements of modeling on effervescent atomization. Their work, entitled "Modeling on effervescent atomization: A review", was published in SCIENCE CHINA, 2011, DOI: 10.1007/s11433-011-4536-1.

Effervescent atomization is a method involving a twin-fluid process that involves bubbling gas within a liquid. Compared to conventional pressure, rotary and twin-fluid atomizers, the effervescent atomizer offers advantages of smaller drop sizes, reduced injection pressure, lower gas flow, a larger exit orifice, and tolerance for high viscosities. Effervescent atomization has been widely used in gas turbine combustors, IC engines furnaces and boilers, incineration, spray deposition, powder formation and other applications. Recently, the effervescent atomization method has been successfully applied in pharmaceutical coating and suspension plasma spray. Because effervescent atomization can handle a variety of liquids, it can play a pivotal role in reducing energy consumption during combustion and has potential for broad applications in the manufacture of high quality materials.

Effervescent atomizer performance has been the object of extensive research since the late 1980s. Studies on the atomization spray can be grouped into two broad categories: diagnostic measurements and numerical modeling. Diagnostic measurements have made a significant contribution to the development of effervescent atomization technology over the past two decades. Fundamental understanding of the spray process is challenging due to the high complexity of two-phase phenomena statistic behavior. Lin and his co-workers from Jiliang University and Zhejiang Universities, China, have devoted their efforts to establish a comprehensive numerical model to explain the phenomena involved in effervescent atomization spray. Their studies cover modeling of liquid fragmentation, the parametric study of various operating conditions, and the development of a fitting formula for droplet mean size and impinging factors.

The effervescent atomization process involves complex fluid-dynamic and transport phenomena. A typical effervescent atomization spray can be divided into four sub-domains, according to the different mechanisms involved. As shown in Fig.1, in the schematic for effervescent atomization spray generation, the first sub-domain is internal-mixing atomization, in which atomizing gas is bubbled into the liquid. The second step is a resulting two-phase mixture that is discharged from the atomizer orifice. Leaving the nozzle exit, the rapidly expanding gas phase will shatter the liquid into fine droplets, which can be referred to as primary atomization. The third domain lies downstream of the spray. The droplets produced by primary atomization are unstable in the turbulent spray and undergo a series of events such as collision, breakup and coalescence, and finally the droplets entrained in the gas jet will impinge on the plate or undergo further mass and heat transfer. Most modeling work has focused on the external two-phase flow out of the effervescent atomizer exit. The review paper focused on the Lagrangian treatment and introduced a comprehensive model capable of describing both primary and secondary breakup processes and correlating the droplet mean diameter and other spray characteristics with first principle operating conditions. The model comprises two sub-models. The first sub-model is used for simulating the primary breakup of the annular liquid sheath near the orifice and calculating the atomized droplet size. The second sub-model is based on a hybrid Eulerian/Lagrangian coordinate system to simulate the turbulent gas jet and injected droplets. This latter sub-model describes the gas jet and the droplet trajectory in three-dimensional geometry and also considers droplet breakup and collision.

The paper reviews the mechanism of droplet events and the numerical treatments of effervescent atomization, which involved the primary atomization of a Newtonian and a non-Newtonian fluid, particle tracking, secondary atomization and droplets collision. A comprehensive three-dimensional model of droplet-gas flow is introduced to describe the evolution of spray in the effervescent atomization spray. The evolution of droplet mean diameter along the axial distance, the mean size and statistical distribution of atomized droplets at cross sections, as well as the change in droplet velocity are calculated and analyzed to reveal their inner driving forces. The influence of operating conditions and liquid physical properties on atomization performance are discussed. The factors that promote the achievement of good atomization effects are identified. Based on the extensive computation, the influences of various operating conditions and liquid physical properties on atomization effects are quantified. The expressions for the Weber number and the K number, which is related to the operating parameters and liquid properties, are deduced. The formula can be used conveniently and effectively to judge the deposition behaviors of droplets onto surfaces for various Newton liquids. In addition to these achievements, the challenges for future numerical research and the scope for further applications are outlined.

Through academic study and modeling, the critical mechanisms and important parameters involved in effervescent atomization have been deeply understood and the applications of effervescent atomization technology have been successfully extended. This research project was mainly supported by the National Natural Science Foundation of China with Grant Nos. 11132008 and 11002136. The development of modeling approaches to atomization spray is based on previous studies involving many researchers from various institutions and universities.

Modeling of the external flow of effervescent atomization can be divided into two sub-models. The first sub-model is used to simulate the primary breakup of the annular liquid sheath near the orifice and calculating the atomized droplet size. The second sub-model is based on a hybrid Eulerian/Lagrangian coordinate system to simulate the turbulent gas jet and injected droplets.

###

See the article: Qian Lijuan, Lin Jianzhong. Modeling on effervescent atomization: A review. Science China Physics, Mechanics & Astronomy, 2011, DOI: 10.1007/s11433-011-4536-1


[ Back to EurekAlert! ] [ | E-mail | Share Share ]

?


AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.


Effervescent atomization spray: Understanding the modeling process [ Back to EurekAlert! ] Public release date: 1-Jan-2012
[ | E-mail | Share Share ]

Contact: Lin Jianzhong
mecjzlin@public.zju.edu.cn
86-571-868-36009
Science in China Press

Understanding the atomization spray process is not only of academic interest but is also important to various industry applications such as combustion, coating, and chemical synthesis. Significant experimental investigations concerning spray behavior have been conducted in the past. Fundamental understanding of the spray process is, however, still lacking and lags behind applications due to the high complexity of its stochastic behavior. Prof. LIN Jianzhong and his group proposed a comprehensive three-dimensional model to predict the droplet mean size and other spray characteristics by describing both primary and secondary atomization. Recently, they reviewed the theories, practical modeling treatments and the main achievements of modeling on effervescent atomization. Their work, entitled "Modeling on effervescent atomization: A review", was published in SCIENCE CHINA, 2011, DOI: 10.1007/s11433-011-4536-1.

Effervescent atomization is a method involving a twin-fluid process that involves bubbling gas within a liquid. Compared to conventional pressure, rotary and twin-fluid atomizers, the effervescent atomizer offers advantages of smaller drop sizes, reduced injection pressure, lower gas flow, a larger exit orifice, and tolerance for high viscosities. Effervescent atomization has been widely used in gas turbine combustors, IC engines furnaces and boilers, incineration, spray deposition, powder formation and other applications. Recently, the effervescent atomization method has been successfully applied in pharmaceutical coating and suspension plasma spray. Because effervescent atomization can handle a variety of liquids, it can play a pivotal role in reducing energy consumption during combustion and has potential for broad applications in the manufacture of high quality materials.

Effervescent atomizer performance has been the object of extensive research since the late 1980s. Studies on the atomization spray can be grouped into two broad categories: diagnostic measurements and numerical modeling. Diagnostic measurements have made a significant contribution to the development of effervescent atomization technology over the past two decades. Fundamental understanding of the spray process is challenging due to the high complexity of two-phase phenomena statistic behavior. Lin and his co-workers from Jiliang University and Zhejiang Universities, China, have devoted their efforts to establish a comprehensive numerical model to explain the phenomena involved in effervescent atomization spray. Their studies cover modeling of liquid fragmentation, the parametric study of various operating conditions, and the development of a fitting formula for droplet mean size and impinging factors.

The effervescent atomization process involves complex fluid-dynamic and transport phenomena. A typical effervescent atomization spray can be divided into four sub-domains, according to the different mechanisms involved. As shown in Fig.1, in the schematic for effervescent atomization spray generation, the first sub-domain is internal-mixing atomization, in which atomizing gas is bubbled into the liquid. The second step is a resulting two-phase mixture that is discharged from the atomizer orifice. Leaving the nozzle exit, the rapidly expanding gas phase will shatter the liquid into fine droplets, which can be referred to as primary atomization. The third domain lies downstream of the spray. The droplets produced by primary atomization are unstable in the turbulent spray and undergo a series of events such as collision, breakup and coalescence, and finally the droplets entrained in the gas jet will impinge on the plate or undergo further mass and heat transfer. Most modeling work has focused on the external two-phase flow out of the effervescent atomizer exit. The review paper focused on the Lagrangian treatment and introduced a comprehensive model capable of describing both primary and secondary breakup processes and correlating the droplet mean diameter and other spray characteristics with first principle operating conditions. The model comprises two sub-models. The first sub-model is used for simulating the primary breakup of the annular liquid sheath near the orifice and calculating the atomized droplet size. The second sub-model is based on a hybrid Eulerian/Lagrangian coordinate system to simulate the turbulent gas jet and injected droplets. This latter sub-model describes the gas jet and the droplet trajectory in three-dimensional geometry and also considers droplet breakup and collision.

The paper reviews the mechanism of droplet events and the numerical treatments of effervescent atomization, which involved the primary atomization of a Newtonian and a non-Newtonian fluid, particle tracking, secondary atomization and droplets collision. A comprehensive three-dimensional model of droplet-gas flow is introduced to describe the evolution of spray in the effervescent atomization spray. The evolution of droplet mean diameter along the axial distance, the mean size and statistical distribution of atomized droplets at cross sections, as well as the change in droplet velocity are calculated and analyzed to reveal their inner driving forces. The influence of operating conditions and liquid physical properties on atomization performance are discussed. The factors that promote the achievement of good atomization effects are identified. Based on the extensive computation, the influences of various operating conditions and liquid physical properties on atomization effects are quantified. The expressions for the Weber number and the K number, which is related to the operating parameters and liquid properties, are deduced. The formula can be used conveniently and effectively to judge the deposition behaviors of droplets onto surfaces for various Newton liquids. In addition to these achievements, the challenges for future numerical research and the scope for further applications are outlined.

Through academic study and modeling, the critical mechanisms and important parameters involved in effervescent atomization have been deeply understood and the applications of effervescent atomization technology have been successfully extended. This research project was mainly supported by the National Natural Science Foundation of China with Grant Nos. 11132008 and 11002136. The development of modeling approaches to atomization spray is based on previous studies involving many researchers from various institutions and universities.

Modeling of the external flow of effervescent atomization can be divided into two sub-models. The first sub-model is used to simulate the primary breakup of the annular liquid sheath near the orifice and calculating the atomized droplet size. The second sub-model is based on a hybrid Eulerian/Lagrangian coordinate system to simulate the turbulent gas jet and injected droplets.

###

See the article: Qian Lijuan, Lin Jianzhong. Modeling on effervescent atomization: A review. Science China Physics, Mechanics & Astronomy, 2011, DOI: 10.1007/s11433-011-4536-1


[ Back to EurekAlert! ] [ | E-mail | Share Share ]

?


AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.


Source: http://www.eurekalert.org/pub_releases/2012-01/sicp-eas112511.php

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