Academic literature on the topic 'LED heat management'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'LED heat management.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "LED heat management"
1
Ekpu, Mathias, Eugene A. Ogbodo, Felix Ngobigha, and Jude E. Njoku. "Thermal Effect of Cylindrical Heat Sink on Heat Management in LED Applications." Energies 15, no. 20 (October 14, 2022): 7583. http://dx.doi.org/10.3390/en15207583.
Full textAbstract:
Light Emitting Diode (LED) applications are increasingly used in various microelectronic devices due to their efficient light generation. The miniaturisation of the LED and its integration into compact devices within the weight limit have resulted in excessive heat generation, and inefficient management of this heat could lead to the failure of the entire system. Passive and/or active heat sinks are used for dissipating heat from the system to the environment to improve performance. An ANSYS design modeller and transient thermal conditions were utilised in this study to design and simulate the LED system. The modeller performs its function by utilising the Finite Element Method (FEM) technique. The LED system considered in this work consists of a chip, thermal interface material, and a cylindrical heat sink. The thickness of the Cylindrical Heat Sink (CHS) fins used in the investigation is between 2 mm and 6 mm, whilst ensuring the mass of heat sinks is not more than 100 g. The input power of the LED chip is between 4.55 W and 25.75 W, as required by some original equipment manufacturers (OEMs). A mesh dependency study was carried out to ensure the results were synonymous with what can be obtained practically. The simulation results suggest that the power ratings did not affect the thermal resistance of the CHS. In addition, the thermal resistance increased with the increased thickness of the CHS fin. The efficiencies of the heat sink were found to increase with an increased thickness of the cylindrical fin and the accuracy between the calculated and simulated thermal efficiency ranges from 84.33% to 98.80%. Evidently, the CHS fin of 6 mm thickness is more efficient than the other CHS fins, as depicted in this study.
2
Buergel, Erich. "LED Design – A Heat Management Challenge for Automobiles." ATZelektronik worldwide 7, no. 2 (April 2012): 20–23. http://dx.doi.org/10.1365/s38314-012-0081-6.
Full text
3
Kintz, K. Andrew, Sara N. Paisner, and M. Shane Thompson. "THERMAL MANAGEMENT SOLUTIONS FOR THE LED MARKET." International Symposium on Microelectronics 2010, no. 1 (January 1, 2010): 000151–55. http://dx.doi.org/10.4071/isom-2010-ta5-paper3.
Full textAbstract:
High-brightness light emitting diodes (LEDs) are challenged with thermal management issues due to increased power and reduced surface area. This has led to the need for new materials with higher thermal conductivity that can quickly remove the heat from the active layer. LORD Corporation has developed two new thermal management materials, a “no pump-out” thermal grease and a low modulus die attach adhesive, as solutions to the heat dissipation problems facing LED manufacturers. These innovative technologies will help engineers solve complex fundamental thermal management problems. A new 4 W/mK silicone thermal grease has been developed with significant resistance to in-package bleed-out or pump-out eliminating the reliability problem most commonly encountered with traditional thermal greases. A new 10–20 W/mK thermal epoxy adhesive has also been developed creating a new class of flexible adhesives with high adhesion. This combination allows the new LORD die attach adhesive to not only effectively transfer heat out of the package, but also to dissipate the stress caused by thermal expansion and contraction during thermal cycling thereby affording improved package reliability.
4
Maaspuro, Mika. "Novel Ideas for Thermal Management of Filament LED Light Bulbs." International Journal of Online and Biomedical Engineering (iJOE) 17, no. 08 (August 16, 2021): 60. http://dx.doi.org/10.3991/ijoe.v17i08.23695.
Full textAbstract:
The thermal conditions of a filament LED retro light bulb has been investigated. In such light bulbs, LEDs are mounted on filaments which have glass or sapphire substrate and are surrounded by yttrium-aluminium-garnet (YAG). Heat management is challenging as a heatsink cannot normally be used. Instead, heat removal is enabled by using helium as the filling gas. As this provides less efficient heat removal than using a heatsink attached directly to an LED module, LEDs operate in filament LED bulbs typically at rather high temperatures. In this paper thermal performance of a typical filament LED bulb has been studied. LED temperatures and gas flows inside the bulb has been resolved for cases of different orientations of the bulb. Thermal conditions for different filling gases have been resolved. All this has been done using finite element method (FEM) simulations. The main target of this study has been to find out novel solutions for thermal management of filament LED bulbs. Two heat removal solutions have been studied, namely the use of an internal heatsink and an internal piezoelectric oscillating cantilever fan. The results show that solutions can indeed reduce temperature of LED chips and increase the lifespan of the LED bulb.
5
Petroski, James. "Advanced Passive Thermal Management for LED Bulb Systems." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, DPC (January 1, 2013): 001277–93. http://dx.doi.org/10.4071/2013dpc-wa34.
Full textAbstract:
The movement to LED lighting systems worldwide is accelerating quickly as energy savings and reduction of hazardous substances (RoHS) increase in importance. Furthering this trend are government regulations, rebate programs and declining prices. The market drive today is to replace light bulbs of common outputs (60W, 75W and 100W) without resorting to Compact Fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19 for fixture retrofitting. This A19 size and shape restriction causes a small heat sink which is only capable of dissipating heat for 60W equivalent LED bulbs with natural convection. 75W and 100W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today's current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7 °C/W. A more efficient method of cooling can be created using a chimney-based design to lower system thermal resistances below 4 °C/W while meeting all other requirements for bulb system design. Numerical studies and test data are in good agreement for various orientations including methods for keeping the chimney partially active in horizontal orientations. Such chimney-based designs are capable of cooling 75W and 100W equivalent LED light bulbs in the limited volume constraints of A19-size devices.
6
Ramesh, Thangamani, Ayyappan Susila Praveen, Praveen Bhaskaran Pillai, and Sachin Salunkhe. "Numerical simulation of heat sinks with different configurations for high power LED thermal management." International Journal for Simulation and Multidisciplinary Design Optimization 13 (2022): 18. http://dx.doi.org/10.1051/smdo/2022009.
Full textAbstract:
This study performed a steady-state numerical analysis to understand the temperature in different heat sink configurations for LED applications. Seven heat sink configurations named R, H-6, H-8, H-10, C, C3, and C3E3 were considered. Parameters like input power, number of fins, heat sink configuration were varied, and their influence on LED temperature distribution, heat sink thermal resistance and thermal interface material temperature were studied. The results showed that the temperature distribution of the H-6 heat sink decreased by 46.30% compared with the Cheat sink for an input power of 16 W. The result of the H-6 heat sink shows that the heat sink thermal resistance was decreased by 73.91% compared with the Cheat sink at 16 W. The lowest interface material temperature of 54.11 °C was achieved by the H-6 heat sink when the input power was used 16 W. The H-6 heat sink exhibited better performance due to more surface area with several fins than other heat sinks.
7
Ding, Xin Rui, Yu Ji Li, Zong Tao Li, Yong Tang, Bin Hai Yu, and Dong Yuan. "The Application of Heat Pipe Heat Sink for High Power LED Lamps." Applied Mechanics and Materials 602-605 (August 2014): 2713–16. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.2713.
Full textAbstract:
LED has been regarded as the next generation lighting source. As for high power LED lamps, heat accumulation will cause a series of problems. Therefore, thermal management is very important for designing a high power LED lamp. Three types of heat sinks are designed by using the finite element analysis (FEA) method for an 180W high power LED lamp. Then the optimized heat sinks are developed and experiments are performed to demonstrate the simulated results. At the same time, the thermal performances with different working angles are investigated experimentally. The heat sink with heat pipe has a better heat dissipation performance than the conventional heat sink under the same input power. The working angles of the lamps greatly influence the thermal performance of each heat sink. For the same heat sink, the temperature varies with different install directions and working angles. Finally, the heat sink with the best thermal performance is recommended. The results have practical significance in designing high power LED lamps.
8
Zhang, Jian Xin, Ping Juan Niu, Da Yong Gao, and Lian Gen Sun. "Research Progress on Packaging Thermal Management Techniques of High Power LED." Advanced Materials Research 347-353 (October 2011): 3989–94. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3989.
Full textAbstract:
In order to dominate the lighting market, LED needs more electrical power to be driven for higher brightness, thereby increasing thermal power dissipation, which contributes to a high heat flux of 85W/cm2 within a recent typical high power LED chip. And the junction temperature has direct influence upon the light output efficiency, device life time, emitting wavelength and reliability of LED. Therefore, effective removal of heat to maintain a safe junction temperature is the key to meet the future flux per LED requirements. Compared with other individual thermal resistances along the thermal path, thermal design for much lower packaging thermal resistance is more critical to improve the performances of LED. In this paper, major present technical researches on packaging thermal management were analyzed for high power LED, and the advantages and shortcomings of these techniques were respectively summarized. Besides, some suggestions were provided for further research in this area.
9
Sauli, Zaliman, Rajendaran Vairavan, and Vithyacharan Retnasamy. "Heat Sink Fin Number Variation Analysis on Single Chip High Power LED." Applied Mechanics and Materials 487 (January 2014): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amm.487.149.
Full textAbstract:
Thermal management of high power LED is crucial the reliability and performance of the LED affected by the heat produced during photon emission. Heat sinks are utilized to dissipate the heat and to lower the operating junction temperature of LED. This paper demonstrates a simulation work done to evaluate the influence heat sink fin number on the junction temperature and stress of single chip LED package using Ansys version 11. The heat sink with fin number of 4 fins, 6 fins and 8 fins were used and compared. Results showed that increase in heat sink fin number significantly reduces the junction temperature of the LED package.
10
Zhao, Xinjie, Yixi Cai, Jing Wang, and Xiao-Hua Li. "EXPERIMENTAL STUDY OF THERMAL MANAGEMENT OF LED AUTOMOTIVE HEADLAMPS USING HEAT PIPES." Heat Transfer Research 47, no. 10 (2016): 975–87. http://dx.doi.org/10.1615/heattransres.2016010569.
Full textDissertations / Theses on the topic "LED heat management"
1
Pryde, James R. "Development of effective thermal management strategies for LED luminaires." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/26687.
Full textAbstract:
The efficacy, reliability and versatility of the light emitting diode (LED) can outcompete most established light source technologies. However, they are particularly sensitive to high temperatures, which compromises their efficacy and reliability, undermining some of the technology s key benefits. Consequently, effective thermal management is essential to exploit the technology to its full potential. Thermal management is a well-established subject but its application in the relatively new LED lighting industry, with its specific constraints, is currently poorly defined. The question this thesis aims to answer is how can LED thermal management be achieved most effectively? This thesis starts with a review of the current state of the art, relevant thermal management technologies and market trends. This establishes current and future thermal management constraints in a commercial context. Methods to test and evaluate the thermal management performance of a luminaire system follow. The defined test methods, simulation benchmarks and operational constraints provide the foundation to develop effective thermal management strategies. Finally this work explores how the findings can be implemented in the development and comparison of multiple thermal management designs. These are optimised to assess the potential performance enhancement available when applied to a typical commercial system. The outcomes of this research showed that thermal management of LEDs can be expected to remain a key requirement but there are hints it is becoming less critical. The impacts of some common operating environments were studied, but appeared to have no significant effect on the thermal behaviour of a typical system. There are some active thermal management devices that warrant further attention, but passive systems are inherently well suited to LED luminaires and are readily adopted so were selected as the focus of this research. Using the techniques discussed in this thesis the performance of a commercially available component was evaluated. By optimising its geometry, a 5 % decrease in absolute thermal resistance or a 20 % increase in average heat transfer coefficient and 10 % reduction in heatsink mass can potentially be achieved . While greater lifecycle energy consumption savings were offered by minimising heatsink thermal resistance the most effective design was considered to be one optimised for maximum average heat transfer coefficient. Some more radical concepts were also considered. While these demonstrate the feasibility of passively manipulating fluid flow they had a detrimental impact on performance. Further analysis would be needed to conclusively dismiss these concepts but this work indicates there is very little potential in pursuing them further.
2
Ha, Min Seok. "Thermal analysis of high power led arrays." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31803.
Full textAbstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Samuel Graham; Committee Member: J. Rhett Mayor; Committee Member: Yogendra Joshi. Part of the SMARTech Electronic Thesis and Dissertation Collection.
3
Sedlář, Tomáš. "Simulace odvodu tepla výkonového prvku do okolí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242159.
Full textAbstract:
The diploma thesis deals with the simulation of heat dissipation for LED Seoul SZ5-P. The heat transfer is discussed first. Further, the issue of thermal management and its design is analyzed. The dependence of LED junction temperature on area of single and double layer printed circuit board is simulated with Ansys Icepak. Additionally, influences of the number and placement of vias on the printed circuit board and aluminum substrate printed circuit board are simulated. Last but not least, the equations describing the dependence of printed circuit board area on desired LED junction temperature are derived. Finally, the values of heat transfer coefficient including convection and radiation are determined for various heat losses and junction temperatures.
4
Raut, Rahul. "Thermal management of heat sensitive components in Pb-free assembly." Diss., Online access via UMI:, 2005.
Find full text
5
李雯靜 and Man-ching Anney Lee. "Effects of the disease management programme with nurse-led heart failure clinic." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40721036.
Full text
6
Lee, Man-ching Anney. "Effects of the disease management programme with nurse-led heart failure clinic." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40721036.
Full text
7
Lioupras, Ioannis, and Eleni Manthou. "Don’t let my Heart bleed! : An event study methodology in Heartbleed vulnerability case." Thesis, Umeå universitet, Institutionen för informatik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-90126.
Full textAbstract:
Due to the rapid evolution of technology, IT software has become incredibly complex. However the human factor still has a very important role on the application of it, since people are responsible to create software. Consequently, software vulnerabilities represent inevitable drawbacks, found to cost extremely large amounts of money to the companies. “Heartbleed” is a recently discovered vulnerability with no prior investigation that answers questions about the impact it has to the companies affected. This paper focuses on the impact of it on the market value of the companies who participated in the vulnerability disclosure process with the help of an event study methodology. Furthermore our analysis investigates if there is a different affection to the value of the company based on the roles those companies had in the process. Our results suggest that the market did not punish the companies about the existence of vulnerability. However the general negative reaction of the market to the incident reflects the importance of a strategic vulnerability disclosure plan for such cases.
8
Dujardin, Pierre-Philippe. "La conduite de projets ordinaires pilotée par les cadres de santé." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAS018.
Full textAbstract:
La littérature décrit l'organisation hospitalière comme complexe et cloisonnée. Elle identifie le cadre de santé (CdS) comme un pivot pour traduire et articuler les différentes logiques professionnelles. Sa fonction est habituellement décrite par son travail quotidien de coordination opérationnel au détriment d'un travail destiné à structurer et améliorer l'organisation.En s'intéressant à la gestion de projet, l'objectif de la thèse est d'identifier le travail de coordination organisationnelle porté par les CdS.Elle s'appuie sur un dispositif pédagogique qui met des étudiants cadres en position de tiers pour explorer un problème organisationnel délégué par un CdS. Suite à la restitution au CdS du travail produit par le tiers, la recherche intervention a suivi la mise en œuvre de 17 projets sur une année.La thèse est organisée autour de quatre articles publiés. Le premier qualifie les bénéfices et limites de l'intervention du tiers. Le second présente les deux manières d'utiliser la production du tiers, révélatrices de la relation entre le projet, le CdS et l'équipe. Le troisième article explore les conditions de la conduite du projet porté par le CdS dans trois dimensions relationnelles : en proximité avec l'équipe soignante, en transversal avec d'autres unités de soins et au niveau institutionnel avec les acteurs administratifs et hiérarchiques. Le quatrième définit, parmi 12 variables, les facteurs qui influencent le résultat du plan d'action mis en œuvre.Les résultats montrent que l'acteur-tiers a permis de reconfigurer les relations collectives dans l'unité de soins et a relancé le CdS dans son pouvoir d'agir. Le succès du projet a été plus fréquent quand il a été présenté à l'équipe et discuté en réunion, c'est-à-dire quand le CdS a été un régulateur des débats et un arbitre. A l'inverse, lorsque le CdS a attendu un soutien institutionnel, ou que la conduite de projet a été prescriptive, sans communication formelle avec les soignants, l'échec a été plus fréquent. Au final 71% des actions ont produit une amélioration opérationnelle.La recherche montre que les attributs de méthodes et sociaux, ne sont pas tous identifiés dans la conduite de projet portée par les CdS. Les résultats permettent de qualifier le travail de coordination produit par le CdS de « Projet ordinaire ».Des préconisations sont formulées. Au niveau institutionnel, il est proposé d'identifier une unité de soutien managérial. Il est souligné l'importance de donner de la visibilité au projet ordinaire et de développer des espaces de discussions. Des activités de formation initiale et continue sont identifiées pour accompagner les futurs CdS et les CdS dans leurs pratiques managérialesLiterature describes hospital organisation as complex and compartmentalised. It identifies the head nurse (HN) as a pivot to translate and articulate various professional logics. Her function is usually described by their daily operational work of coordination to the detriment of a job destined to structure and improve organisation.By focusing on project management, the aim of this thesis is to identify the work of organisational coordination carried by the HN.It leans on an educational device which puts student executives in the position of a third party to explore an organisational problem delegated by a HN. After the restitution to the HN produced by a third party, research intervention has followed the implantation of 17 projects over one year.The thesis is organised around four published articles: the first one prones the benefits and limits of the third party intervention. The second presents two methods to use the third party production, revealing the link between the project, the HN and the team. The third article explores the conditions of project management carried by the HN in three relational dimensions: in relation to the medical team, in cross section with other units of care, and at institutional level with the administrative and hierarchical actors. The fourth defines, among 12 variables, the factors which influence the result of the implemented action plan.The results show that the third party allowed to re-configure the collective relations in the unit of care and relaunched the HN in his power to act. The success of the project was more frequent when it was presented to the team and discussed in meetings, that is, when the HN helped regulate debates and be referee. On the contrary, when the HN waited for institutional support, or when the project management was prescriptive, without formal communication with the nursing staff, failure was more frequent. In summary, 71 % of the actions encountered resulted in an operational improvement.The research shows that the attributes of methods and social are not all identified in the project management carried by the HN. The results permit to consider the work of coordination produced by the HN as « ordinary Project ».Recommendations are formulated. At an institutional level, it is suggested to identify a unit managerial support. The proposals underline the importance of giving visibility to the ordinary project and necessity to develop spaces of discussion. Activities of initial and continuous training are identified to accompany the future HN and the HN in their managerial practices
9
Corones, Watkins Katina Marlene. "A randomised controlled clinical trial of a post-discharge, nurse-led educational intervention to reduce anxiety and enhance self-efficacy in percutaneous coronary intervention (PCI) patients within the first week post-discharge: A pilot study." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/93369/1/Katina_Corones-Watkins_Thesis.pdf.
Full textAbstract:
This research investigated the efficacy of a post-discharge nurse-led clinic, for patients who underwent a cardiovascular interventional procedure in Australia. A randomised controlled clinical trial measured the effects of the clinic on patient confidence to self-manage and minimise psychological distress given the strong link between anxiety, depression and coronary heart disease. Hospitalisation for the procedure is short and stressful, and patients may wait up to 7-64 days for post-discharge review. This study provides preliminary quantitative and qualitative evidence that nurse-led clinics undertaken within the first week post-percutaneous coronary intervention may fill a much-needed gap for patients during a potentially vulnerable period.
10
Berggren, Josefine, and Elin Jakobsson. "“Vi leder på ett helt annat sätt än man någonsin har gjort förut” : En studie om chefers upplevelse av att leda i krissituationer inom detaljhandeln." Thesis, Uppsala universitet, Institutionen för pedagogik, didaktik och utbildningsstudier, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414044.
Full textAbstract:
Denna studie syftar till att bidra med kunskap om hur chefer upplever ledarskap i krissituationer. Studien närmar sig syftet genom att ta utgångspunkt i följande tre frågeställningar: Hur upplever chefer att deras ledarskap förändras i kris? Vilka utmaningar och problem uppstår i krissituationer? Vilka typer av strategier använder chefer för att möta de utmaningar och problem som uppstår i kris? Vi har utgått från krisen som orsakas av Covid-19 pandemin under 2020, men vår ambition är att resultatet ska kunna appliceras även på andra typer av kriser. Studien bedrivs med en kvalitativ ansats där semistrukturerade intervjuer används som datainsamlingsmetod. Materialet har analyserats genom en tematisk analys med grund i studiens teoretiska ramverk; Situationsanpassat ledarskap II. Historiskt är ledarskap ett välbeforskat område med stor variation i både infallsvinklar och fenomen som har undersökts. Vår studie ämnar undersöka ledarskap i kris och hur detta upplevs av dem som utövar det, vilket är en del i fältet som tycks vara tämligen outforskat. Det är sedan tidigare fastställt att ledarskap och ledare har en avgörande roll i kris. Resultatet i vår studie visar att cheferna tvingats ändra sitt ledarskap som en konsekvens av krisen och de använder sig främst av en styrande ledarskapsstil. Upplevelsen av den förändringen skiljer sig mellan cheferna, där några upplever att krisen utmanat dem på ett roligt sätt och andra menar att ledarskapet nu är helt skilt från hur de vill leda. Hos de chefer som menar att krisen varit delvis rolig kan vi identifiera en konflikt mellan vilken ledare de uttrycker att de vill vara och vilken ledare de känner tillfredsställelse av att vara. Cheferna använder olika strategier för att möta de utmaningar som uppstår, men kommunikation tycks vara den främsta. Studien fastställer också att många pedagogiska processer har blivit lidande under krisen, som en konsekvens av att cheferna inte hinner individanpassa sitt ledarskap.The aim of this study is to contribute with knowledge about how managers experience leadership in crisis. The study approaches the purpose by asking the following questions: How do managers experience that their leadership changes in crisis? What challenges and problems arise in crisis? What type of strategies do managers use to meet the challenges and problems that arise in crisis? The study is referring to the crisis caused by the Covid-19 pandemic in 2020, however our ambition is that the result should also be applicable to other types of crises. The study is conducted with a qualitative approach where semi-structured interviews are used as a method for data collection. The material has been analyzed through a thematic analysis based on the theoretical framework of the study; Situational leadership II. Historically, leadership has been a well-researched area with considerable variation in both approaches and phenomena. Our study aims to explore leadership in crisis and how this is experienced by those who practice it, which is part of the field that seems to be fairly unexplored. What has been established in earlier studies is that leadership play a crucial role in crisis. Our result shows that the managers were forced to change their leadership as a consequence of the crisis, and they mainly use a directing leadership style. The experience of this change differs among the managers, where some feel that the crisis has challenged them in a fun way and others feel that the leadership is now completely different from how they want to lead. Among the leaders who think the crisis has been partially fun we can identify a conflict when it comes to which leader they express they want to be and which leader they feel satisfaction of being. The leaders tend to use different types of strategies to face the challenges as a consequence of the crisis, the most common one seems to be communication. The study also states that many educational processes have suffered during the crisis, as a consequence of the leaders not being able to adapt their leadership to meet the individual needs of their followers.
Books on the topic "LED heat management"
1
Lead from the heart: Transformational leadership for the 21st century. Bloomington: Balboa Press, 2011.
Find full text
2
Christine, Muhlke, ed. On the line: The heart and soul of a four-star restaurant. New York, NY: Artisan, 2008.
Find full text
3
Crisis in organizations: Managing and communicating in the heat of chaos. Cincinnati: South-Western Pub. Co., 1993.
Find full text
4
You can hear me now: How microloans and phones are connecting the world's poor to the global economy. San Francisco: Jossey-Bass, 2007.
Find full text
5
Committee, New Jersey Legislature General Assembly Regulatory Oversight. Committee meeting of Assembly Regulatory Oversight Committee: Testimony concerning activities of the Budget Efficiency Savings Team Commission; testimony concerning public access to individual state trooper records; and testimony addressing regulations dealing with head injury victims. Trenton, N.J: Office of Legislative Services, Public Information Office, Hearing Unit, 2002.
Find full text
6
Crowley, Mark C. Lead from the Heart. Hay House, Incorporated, 2022.
Find full text
7
Crowley, Mark C. Lead from the Heart : : Transformational Leadership for the 21St Century. Balboa Press, 2011.
Find full text
8
Gartland, Tom. Lead with Heart: Transform Your Business Through Personal Connection. BenBella Books, 2018.
Find full text
9
Morris, Rhiain. Psychological management of coronary heart disease. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0123.
Full textAbstract:
Both anxiety and depression have been found to increase the risk of developing coronary heart disease (CHD) and lead to exacerbation of cardiac symptoms, with the latter subsequently impacting recovery/rehabilitation (e.g. leading to an increased number of readmissions to hospital, and an increased mortality risk following myocardial infarction (MI)). This may be due to pathophysiologic effects, such as vascular inflammation and autonomic dysfunction, and poor lifestyle/behavioural patterns, including non-attendance at cardiac rehabilitation classes; and/or poor treatment adherence. Psychosocial factors such as stress, hostility, social isolation, socio-economic status, and psychological defensiveness can also affect the course of cardiac illness.
10
Roques, Tom. Oncological management of head and neck cancer III. Edited by John Phillips and Sally Erskine. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198834281.003.0053.
Full textAbstract:
This chapter discusses Pignon, le Maître, Maillard, and Bourhis’s paper on meta-analysis of chemotherapy in head and neck cancer including the design of the study (outcome measures, results, conclusions, and a critique).
Book chapters on the topic "LED heat management"
1
Palmer, George. "Pacemaker Lead Management Strategies." In Atlas of Adult Congenital Heart Surgery, 255–69. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-14163-9_13.
Full text
2
Kirchhelle, Claas. "Ruth the Ruthless: Activism, Welfare, and Generational Change." In Palgrave Studies in the History of Social Movements, 149–74. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-62792-8_9.
Full textAbstract:
AbstractThis chapter studies the polarisation of 1970s’ British farm animal welfare politics and Ruth Harrison’s career as a full-time public campaigner on the RSPCA Council and as head of her own welfare Trust. Polarised conflicts triggered a professionalisation of RSPCA campaigning. The Society adopted new public pressure tactics, established expert committees, and started commissioning behavioural research. Internal tensions over elite “field sports” also led to the formation of the RSPCA Reform Group. Reform Group members oversaw a streamlining of RSPCA management and leadership. They also popularised animal rights thinking. Ruth Harrison supported opposition to “field sports” and helped trigger the internal crisis that led to the Reform Group’s formation. However, tensions over her role on FAWAC and her focus on gradualist reforms isolated Harrison. Forced to declare bankruptcy after a libel suit against another Council member, Harrison focused on developing her own Farm Animal Care Trust (FACT).
3
Rischin, Danny. "Update of Immune Therapies in Recurrent/Metastatic Head and Neck Cancer." In Critical Issues in Head and Neck Oncology, 297–306. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63234-2_19.
Full textAbstract:
AbstractSince the initial reports of activity of pembrolizumab in recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC), investigation of the role of immune therapies has been the major focus of clinical trials in R/M HNSCC. Randomised trials initially with nivolumab and later with pembrolizumab established overall survival benefit in patients with R/M HNSCC previously treated with platinum compared to physicians choice of 2nd line therapy, and have led to regulatory approval around the world. More recently the Keynote-048 trial has compared both pembrolizumab monotherapy and pembrolizumab + platinum/5FU to the Extreme regimen of platinum/5FU/cetuximab in the first-line R/M setting. The key findings from this trial are that pembrolizumab monotherapy compared to Extreme improved overall survival in patients with PD-L1 combined positive score (CPS) ≥ 20 and ≥ 1, and that pembro/chemotherapy improved OS in CPS ≥ 20, CPS ≥ 1 and the total population. Relative to Extreme there was less toxicity in the monotherapy arm and comparable toxicity in the pembro/chemo arm. Based on this trial use of pembrolizumab as part of first-line treatment for R/M HNSCC is appropriate for the majority of patients, and represents a new standard of care. The focus has now moved to identifying combinations that may be superior to pembrolizumab monotherapy or to chemotherapy + pembrolizumab. Some of the more promising approaches under investigation in HNSCC are discussed in this chapter. In summary, immune therapies are now the cornerstone of management of R/M HNSCC with the approval of pembrolizumab in the first-line R/M setting.
4
Vesanen, Teemu, Kiviniemi Markku, Kostas Tsatsakis, and Gabriele Masera. "Digital Tools for Fast-Track Renovation Operations." In Innovative Tools and Methods Using BIM for an Efficient Renovation in Buildings, 75–94. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04670-4_6.
Full textAbstract:
AbstractDigital tools for fast-track renovation operations developed in the project aim to shorten the duration of renovation and disturbance to the occupants with BIM-enabled methods and tools in operations management at site and with prefabrication to speed up the installation tasks. The chapter presents an ensemble of tools, concepts and use cases. First, two tools are described that are used to support construction production management and user communication. Then a concept how product data could be used as part of the tools and further how the product data and the tools could support in achieving the overall BIM4EEB objectives in the use cases of prefabricated exhaust air heat pump and prefabricated thermal insulation. Target of the work was to improve the state-of-the-art planning and monitoring. A new tool was created that combines the BIM model and typical work breakdown structure (WBS) based project scheduling into location breakdown structure (LBS) based user-interface. Continuously updated LBS provide valuable information to stakeholders with web-service and mobile applications. The 24/7 situational awareness of the renovation activities status provides unprecedented transparency of the project progress. Hence, the system allows scheduling the site activities with shorter lead times to shorten the total construction duration while it is possible to immediately take control of possible deviations in implementation. The reliable progress data is available also to the clients and occupants with right timed guidance and safety instructions. The other aim in the work was to utilise BIM for increasing the share of prefabrication in renovation projects. The BIM-based design allows to manage the compatibility and tolerances between design disciplines and adapting those with mapped geometry of the building will enable the prefabrication and preassembling of structural and system components also in renovation. Two best practice examples were developed and described showing how to utilise prefabrication in real renovation scenarios.
5
Byrne, Jill. "Nurse-Led Innovation to Reduce Occupational Heat Stress of Operating Room Personnel." In Nurse Leadership and Management. New York, NY: Springer Publishing Company, 2022. http://dx.doi.org/10.1891/9780826177957.0024d.
Full text
6
González-Palma, Rafael, María Carmen Carnero, Carlos López-Escobar, David Almorza, and Pedro Mayorga. "Compatibility Welding Parameters with the Results Obtained in Testing of Fracture Mechanics in HSLA Steel." In Optimum Decision Making in Asset Management, 163–93. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0651-5.ch008.
Full textAbstract:
Many investigations led to show that no crack begins to propagate to an increase of stress intensity factor. The life of the components of a structure containing premature cracks, can be governed by the degree of subcritical crack propagation. Thus, knowledge of crack propagation to determine the fatigue of the structure is necessary. One problem of steels of high resilience is their low toughness in the HAZ, when they are welded with a high heat input. In this work we have studied nine specimens that have been welded under a submerged arc welding process controlling the welding parameters and checking in the HAZ of such specimens, critical tensions at the ends of the cracks, the critical cracks lengths and stress intensity factors. It is intended to check that the parameters that indicate the values of fracture mechanics in the HAZ, after heat cycle to which the steel has undergone, under a process with a maximum heat input of 2.327kJ /mm, they are still valid, with the welding parameters applied. It is checked a correlation between the theoretical and experimental values.
7
Chul Cha, Sung, Kyoung Il Moon, and Hae Won Yoon. "Current Development of Automotive Powertrain Components for Low Friction and Wear Reduction through Coating and Heat Treatment Technology." In Lubrication - Thermal Management and Friction Reduction [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106032.
Full textAbstract:
Recent findings of R&D for powertrain components concerning friction and wear reduction are described in this chapter. These are realized through lubrication technology of coating and heat treatment, which are fit for this book. In the first part, nano-complex coatings for parts of future mobility are presented with their friction and wear behavior. The application of an alloying target was proposed to promote the commercial use of nanocomposite coatings. In the second part, the importance on pre-treatments-related silicon oxide-diamond-like carbon (SiO-DLC) coating for the smallest part of fuel system is described. The optimization of cleaning for the balls before coating was resulted: The best cleaning performance presented the addition of acetone cleaning, water boiling, and then acetone cleaning, confirmed by fluorescence analyzers. The third part of this work was developing low-temperature vacuum carburizing and pre-treatment for parts of injector, stopper (SUS303), and position ring (1.4305) with high wear resistance. The difference between two steels led to the result: high molybdenum of 1.4305 formed Mo-oxides on the surface during acid etching. These Mo-oxides resolved quickly by hydrogen during carburizing and then enabled activated carburizing. The 1.4305 was appropriate for the carburizing and was chosen for stopper.
8
Pais, Silvana, João Campos, Judit Lecina, and Adrián Regos. "Fire-smart management as nature-based solution to extreme wildfires in abandoned rural landscapes of Southern Europe." In Advances in Forest Fire Research 2022, 1634–39. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_250.
Full textAbstract:
The continuous research and development regarding firefighters’ personal protective equipment (PPE) has led to significant improvements in recent decades. The findings that contributed the most to the firefighters’ protective clothing evolution, increasing the protection, were the use of high-performance fibers, flame-retardant polymer fibers and the changes on clothing structure namely the incorporation of a multi-layer system. Despite the evolution of firefighters PPE, every year an undesirable number of firefighters are seriously burned during firefighting operations with some of them eventually losing their life. Therefore, the need to proceed the research and development regarding thermal protective clothing arises, to increase firefighters’ protection and consequently minimize firefighters’ heat load and skin burn. Firefighters’ protection can be further increased with the incorporation of smart textiles in the personal protective equipment, such as integrated sensors to monitor parameters such as heart rate, oxygen saturation, carbon dioxide detector and setting real-time communication with a command post. In addition to the wearable electronics, regarding smart textiles alternatives for firefighters PPE, several studies have been conducted to incorporate phase change materials (PCM) in firefighters thermal protective clothing with satisfactory results. These advanced materials will absorb the heat from the fire leading to a reduction of the amount of heat to which firefighters are exposed to and an increase of the time that firefighters can be exposed to heat. The evolution of firefighters PPE has been followed by an evolution and update of the international and national standards that specify performance requirements for firefighters’ protective clothing for structural and wildland firefighting as well as technical rescue. In respect to structural firefighting, the applicable European standard is EN 469:2020: Protective clothing for firefighters – Performance requirements for protective clothing for firefighters’ activities and regarding the wildland firefighting, the international standard prevailing is EN ISO 15384:2020: Protective clothing for firefighters – Laboratory test methods and performance requirements for wildland firefighting clothing. For technical rescue the applicable European standard is EN 16689: 2017: Protective clothing for firefighters – Performance requirements for protective clothing for technical rescue. Given the growing trend towards the incorporation of smart materials in firefighters PPE is important to study and develop new standards to certify these innovative protective clothing for firefighters, regardless the efforts being done within CEN / TC 248/WG 31 - Smart Textiles. To preserve the protection of firefighters protective clothing there are some actions that must be taken during the protective garments’ life cycle. Therefore, recently was developed a technical report, a CEN/ TR1760:2021 that describes the guidelines for selection use, care and maintenance of smart garments protecting against heat and flame. This study will focus on the analysis of firefighters protective clothing evolution regarding the use and integration of advanced smart materials, namely phase change materials, taking in consideration the evolution and requirements of international and European standards as well as national legislation for firefighters’ protective clothing.
9
Jaarsma, Tiny. "Nurse-led management programmes in heart failure." In Caring for the Heart Failure Patient, 161–80. CRC Press, 2004. http://dx.doi.org/10.3109/9780203640630-13.
Full text
10
Vazir, Ali, and Suzanna Hardman. "Multidisciplinary heart failure management programmes." In Oxford Textbook of Heart Failure, edited by Andrew L. Clark, Roy S. Gardner, and Theresa A. McDonagh, 799–808. Oxford University Press, 2022. http://dx.doi.org/10.1093/med/9780198766223.003.0064.
Full textAbstract:
This chapter evaluates the multidisciplinary approach to the management of people with heart failure. A critical reading of the literature on multidisciplinary heart failure management programmes and recognition of its limitations should not in any way discourage, but rather support, the establishment of effective and responsive multidisciplinary teams for the care of people with known or suspected heart failure. To date, the emphasis has been on community-based teams, but a number of studies and emerging audit data argue powerfully, in addition, for an improvement in hospital care. Best outcomes are achieved when patients are actively identified; where ongoing care, including early echocardiography, is led by a (heart failure) cardiologist; and where patients can be managed in a specialist ward with access to a range of healthcare professionals to ensure rapid stabilization and inpatient optimization of treatment. As the patient recovers, opportunities for education arise and should be embraced. Discharge planning should include plans for primary care and cardiology review, rehabilitation, uptitration of medication, and ongoing opportunities for individual patients to understand their condition.
Conference papers on the topic "LED heat management"
1
Treurniet, Theo, and Karel Joop Bosschaart. "Method for heat flux measurement on LED light engines." In Management Symposium (SEMI-THERM). IEEE, 2011. http://dx.doi.org/10.1109/stherm.2011.5767213.
Full text
2
Ma, H. K., B. R. Chen, H. W. Lan, and C. Y. Chao. "Study of an LED device with a honeycomb heat sink." In 2010 IEEE/CPMT 26th Semiconductor Thermal Measurement, Modeling & Management Symposium (SEMI-THERM). IEEE, 2010. http://dx.doi.org/10.1109/stherm.2010.5444277.
Full text
3
Pounds, Dan, and Richard W. Bonner. "High heat flux heat pipes embedded in metal core printed circuit boards for LED thermal management." In 2014 IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm). IEEE, 2014. http://dx.doi.org/10.1109/itherm.2014.6892291.
Full text
4
Thungod, Chaiyant, Apicha Tuptimkaew, Manrat Rattanachan, Sucheep Buaban, Darinee Loakhen, Phatsaphon Wansungnoen, Pramote Pattanapongthong, and Werachet Khan-ngern. "Design of heat management model of 6,000 lumen LED worklamp using integrated SEPIC drivers." In 2014 International Electrical Engineering Congress (iEECON). IEEE, 2014. http://dx.doi.org/10.1109/ieecon.2014.6925874.
Full text
5
Zhang Kai, Matthew M. F. Yuen, David G. W. Xiao, Y. Y. Fu, and Philip Chan. "Directly synthesizing CNT-TIM on aluminum alloy heat sink for HB-LED thermal management." In 2008 58th Electronic Components and Technology Conference (ECTC 2008). IEEE, 2008. http://dx.doi.org/10.1109/ectc.2008.4550200.
Full text
6
Sahu, Gopinath, Sameer Khandekar, Krishnamurthy Muralidhar, and Elizaveta Ya Gatapova. "HEAT TRANSFER INVESTIGATION OF SPRAY COOLING FOR THERMAL MANAGEMENT OF A HIGH POWER LED MODULE." In 5-6th Thermal and Fluids Engineering Conference (TFEC). Connecticut: Begellhouse, 2021. http://dx.doi.org/10.1615/tfec2021.fip.032170.
Full text
7
Kudsieh, N., M. Khizar, and M. Yasin Akhtar Raja. "Novel graphene heat spreaders for the thermal management of micro-LED arrays for optical communication." In 2014 11th Annual High-capacity Optical Networks and Emerging/Enabling Technologies (HONET). IEEE, 2014. http://dx.doi.org/10.1109/honet.2014.7029366.
Full text
8
Sathyanarayana, Aravind, Yogendra Joshi, and Yunhyeok Im. "Pool Boiling of Mixtures for Electronics Thermal Management." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22950.
Full textAbstract:
Electrical and chemical compatibility requirements of electronic components pose significant constraints on the choice of liquid coolants. These constraints have led to the use of fluoroinerts and Novec liquids as coolants, which are plagued by significantly lower thermal conductivity, specific heat, and latent heat of vaporization compared to water, and also a number of these chemicals have significant environmental impact. These factors necessitate the development of new heat transfer fluids with improved heat transfer properties and applicability. Mixture formulations provide an avenue for enhancing the properties of existing heat transfer fluids. These can be tuned for specific applications. Mixture formulations of Novec fluid (HFE 7200) with alcohols and ethers (HFE 7200 and methanol; HFE 7200 and ethoxybutane) are considered in this study. A 1 cm × 1 cm Silicon (Si) sample having copper nanowire arrays is used as the test surface for pool boiling. Experiments are done under saturated conditions and also at different sub-cooled conditions to investigate the thermal performance of these new fluid mixtures. Pool boiling heat transfer performance and the critical heat flux are measured for fluid mixtures and compared with the corresponding base fluid. From the pool boiling experiments, it was observed that adding methanol to pure HFE 7200 enhances the CHF of the resulting mixture and adding ethoxybutane to pure HFE 7200 reduces the incipience temperature for boiling.
9
Zhang, Kai, and Matthew M. F. Yuen. "Heat Spreader with Aligned CNTs Designed for Thermal Management of HB-LED Packaging and Microelectronic Packaging." In 2006 7th International Conference on Electronic Packaging Technology. IEEE, 2006. http://dx.doi.org/10.1109/icept.2006.359779.
Full text
10
Chiang, S. B., M. C. Lu, W. L. Wu, M. C. Yen, and C. C. Wang. "A Numerical and Experimental Study of the Thermal Management of LEDs." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61354.
Full textAbstract:
This study examines the thermofluids characteristics of a LED lighting device. It is found that the heat sources of the present LED lighting are from the PCB and from the LED itself. To effectively improve the overall performance of the LED device, it is suggested that these two heat sources should be dealt with separately. For efficient thermal management of the LED, it is recommended to use the insulators and separate sink. The former can effectively block the heat flow from the PCB to LED panel where the latter can maintain the temperatures of PCB and LED within tolerable limit.
Reports on the topic "LED heat management"
1
Eberle, Caitlyn, and Oscar Higuera Roa. Technical Report: Mediterranean wildfires. United Nations University - Institute for Environment and Human Security (UNU-EHS), August 2022. http://dx.doi.org/10.53324/vceb1752.
Full textAbstract:
In summer 2021, drought and low humidity combined with record-breaking heat of up to 48.8°C (119.8°F) led to fire outbreaks across the Mediterranean countries, killing more than 100 people and burning more than 620,000 ha of land in July and August. As forests are often fiercely protected areas, the common approach to wildfire management in the Mediterranean is to extinguish every fire as it appears, but counterintuitively this supports the formation of “mega-fires” that burn beyond our capacity to control. Fires are not yet seen as integral to ecosystem functioning, and the management of fires and fires are often disconnected. This technical background report for the 2021/2022 edition of the Interconnected Disaster Risks report analyses the root causes, drivers, impacts and potential solutions for the Mediterranean wildfires through a forensic analysis of academic literature, media articles and expert interviews.
2
Yahav, Shlomo, John Brake, and Noam Meiri. Development of Strategic Pre-Natal Cycling Thermal Treatments to Improve Livability and Productivity of Heavy Broilers. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7593395.bard.
Full textAbstract:
The necessity to improve broiler thermotolerance and live performance led to the following hypothesis: Appropriate comprehensive incubation treatments that include significant temperature management changes will promote angiogenesis and will improve acquisition of thermotolerance and carcass quality of heavy broilers through epigenetic adaptation. It was based on the following questions: 1. Can TM during embryogenesis of broilers induce a longer-lasting thermoregulatory memory (up to marketing age of 10 wk) that will improve acquisition of thermotolerance as well as increased breast meat yield in heavy broilers? 2. The improved sensible heat loss (SHL) suggests an improved peripheral vasodilation process. Does elevated temperature during incubation affect vasculogenesis and angiogenesis processes in the chick embryo? Will such create subsequent advantages for heavy broilers coping with adverse hot conditions? 3. What are the changes that occur in the PO/AH that induce the changes in the threshold response for heat production/heat loss based on the concept of epigenetic temperature adaptation? The original objectives of this study were as follow: a. to assess the improvement of thermotolerance efficiency and carcass quality of heavy broilers (~4 kg); b. toimproveperipheral vascularization and angiogenesis that improve sensible heat loss (SHL); c. to study the changes in the PO/AH thermoregulatory response for heat production/losscaused by modulating incubation temperature. To reach the goals: a. the effect of TM on performance and thermotolerance of broilers reared to 10 wk of age was studied. b. the effect of preincubation heating with an elevated temperature during the 1ˢᵗ 3 to 5 d of incubation in the presence of modified fresh air flow coupled with changes in turning frequency was elucidated; c.the effect of elevated temperature on vasculogenesis and angiogenesis was determined using in ovo and whole embryo chick culture as well as HIF-1α VEGF-α2 VEGF-R, FGF-2, and Gelatinase A (MMP2) gene expression. The effects on peripheral blood system of post-hatch chicks was determined with an infrared thermal imaging technique; c. the expression of BDNF was determined during the development of the thermal control set-point in the preoptic anterior hypothalamus (PO/AH). Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” Recently, Piestunet al. (2008) demonstrated for the first time that TM (an elevated incubation temperature of 39.5°C for 12 h/d from E7 to E16) during the development/maturation of the hypothalamic-hypophyseal-thyroid axis (thermoregulation) and the hypothalamic-hypophyseal-adrenal axis (stress) significantly improved the thermotolerance and performance of broilers at 35 d of age. These phenomena raised two questions that were addressed in this project: 1. was it possible to detect changes leading to the determination of the “set point”; 2. Did TM have a similar long lasting effect (up to 70 d of age)? 3. Did other TM combinations (pre-heating and heating during the 1ˢᵗ 3 to 5 d of incubation) coupled with changes in turning frequency have any performance effect? The improved thermotolerance resulted mainly from an efficient capacity to reduce heat production and the level of stress that coincided with an increase in SHL (Piestunet al., 2008; 2009). The increase in SHL (Piestunet al., 2009) suggested an additional positive effect of TM on vasculogenesis and angiogensis. 4. In order to sustain or even improve broiler performance, TM during the period of the chorioallantoic membrane development was thought to increase vasculogenesis and angiogenesis providing better vasodilatation and by that SHL post-hatch.
3
Yahav, Shlomo, John McMurtry, and Isaac Plavnik. Thermotolerance Acquisition in Broiler Chickens by Temperature Conditioning Early in Life. United States Department of Agriculture, 1998. http://dx.doi.org/10.32747/1998.7580676.bard.
Full textAbstract:
The research on thermotolerance acquisition in broiler chickens by temperature conditioning early in life was focused on the following objectives: a. To determine the optimal timing and temperature for inducing the thermotolerance, conditioning processes and to define its duration during the first week of life in the broiler chick. b. To investigate the response of skeletal muscle tissue and the gastrointestinal tract to thermal conditioning. This objective was added during the research, to understand the mechanisms related to compensatory growth. c. To evaluate the effect of early thermo conditioning on thermoregulation (heat production and heat dissipation) during 3 phases: (1) conditioning, (2) compensatory growth, (3) heat challenge. d. To investigate how induction of improved thermotolerance impacts on metabolic fuel and the hormones regulating growth and metabolism. Recent decades have seen significant development in the genetic selection of the meat-type fowl (i.e., broiler chickens); leading to rapid growth and increased feed efficiency, providing the poultry industry with heavy chickens in relatively short growth periods. Such development necessitates parallel increases in the size of visceral systems such as the cardiovascular and the respiratory ones. However, inferior development of such major systems has led to a relatively low capability to balance energy expenditure under extreme conditions. Thus, acute exposure of chickens to extreme conditions (i.e., heat spells) has resulted in major economic losses. Birds are homeotherms, and as such, they are able to maintain their body temperature within a narrow range. To sustain thermal tolerance and avoid the deleterious consequences of thermal stresses, a direct response is elicited: the rapid thermal shock response - thermal conditioning. This technique of temperature conditioning takes advantage of the immaturity of the temperature regulation mechanism in young chicks during their first week of life. Development of this mechanism involves sympathetic neural activity, integration of thermal infom1ation in the hypothalamus, and buildup of the body-to-brain temperature difference, so that the potential for thermotolerance can be incorporated into the developing thermoregulation mechanisms. Thermal conditioning is a unique management tool, which most likely involves hypothalamic them1oregulatory threshold changes that enable chickens, within certain limits, to cope with acute exposure to unexpected hot spells. Short-tem1 exposure to heat stress during the first week of life (37.5+1°C; 70-80% rh; for 24 h at 3 days of age) resulted in growth retardation followed immediately by compensatory growth" which resulted in complete compensation for the loss of weight gain, so that the conditioned chickens achieved higher body weight than that of the controls at 42 days of age. The compensatory growth was partially explained by its dramatic positive effect on the proliferation of muscle satellite cells which are necessary for further muscle hypertrophy. By its significant effect of the morphology and functioning of the gastrointestinal tract during and after using thermal conditioning. The significant effect of thermal conditioning on the chicken thermoregulation was found to be associated with a reduction in heat production and evaporative heat loss, and with an increase in sensible heat loss. It was further accompanied by changes in hormones regulating growth and metabolism These physiological responses may result from possible alterations in PO/AH gene expression patterns (14-3-3e), suggesting a more efficient mechanism to cope with heat stress. Understanding the physiological mechanisms behind thermal conditioning step us forward to elucidate the molecular mechanism behind the PO/AH response, and response of other major organs. The thermal conditioning technique is used now in many countries including Israel, South Korea, Australia, France" Ecuador, China and some places in the USA. The improvement in growth perfom1ance (50-190 g/chicken) and thermotolerance as a result of postnatal thermal conditioning, may initiate a dramatic improvement in the economy of broiler's production.
4
VanderGheynst, Jean, Michael Raviv, Jim Stapleton, and Dror Minz. Effect of Combined Solarization and in Solum Compost Decomposition on Soil Health. United States Department of Agriculture, October 2013. http://dx.doi.org/10.32747/2013.7594388.bard.
Full textAbstract:
In soil solarization, moist soil is covered with a transparent plastic film, resulting in passive solar heating which inactivates soil-borne pathogen/weed propagules. Although solarization is an effective alternative to soil fumigation and chemical pesticide application, it is not widely used due to its long duration, which coincides with the growing season of some crops, thereby causing a loss of income. The basis of this project was that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. In this research we examined three factors expected to contribute to greater utilization of solarization: 1) investigation of techniques that increase soil temperature, thereby reducing the time required for solarization; 2) development and validation of predictive soil heating models to enable informed decisions regarding soil and solarization management that accommodate the crop production cycle, and 3) elucidation of the contributions of microbial activity and microbial community structure to soil heating during solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays, and samples were subjected to 16S ribosomal RNA gene sequencing to characterize microbial communities. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO2/g dry weight organic carbon resulted in soil temperatures that were 2oC to 4oC higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. The sequencing data obtained from field samples revealed similar microbial species richness and evenness in both solarized amended and non-amended soil. However, amendment led to enrichment of a community different from that of non-amended soil after solarization. Moreover, community structure varied by soil depth in solarized soil. Coupled with temperature data from soil during solarization, community data highlighted how thermal gradients in soil influence community structure and indicated microorganisms that may contribute to increased soil heating during solarization. Reliable predictive tools are necessary to characterize the solarization process and to minimize the opportunity cost incurred by farmers due to growing season abbreviation, however, current models do not accurately predict temperatures for soils with internal heat generation associated with the microbial breakdown of the soil amendment. To address the need for a more robust model, a first-order source term was developed to model the internal heat source during amended soil solarization. This source term was then incorporated into an existing “soil only” model and validated against data collected from amended soil field trials. The expanded model outperformed both the existing stable-soil model and a constant source term model, predicting daily peak temperatures to within 0.1°C during the critical first week of solarization. Overall the results suggest that amendment of soil with compost prior to solarization may be of value in agricultural soil disinfestations operations, however additional work is needed to determine the effects of soil type and organic matter source on efficacy. Furthermore, models can be developed to predict soil temperature during solarization, however, additional work is needed to couple heat transfer models with pathogen and weed inactivation models to better estimate solarization duration necessary for disinfestation.
5
Halevy, Orna, Zipora Yablonka-Reuveni, and Israel Rozenboim. Enhancement of meat production by monochromatic light stimuli during embryogenesis: effect on muscle development and post-hatch growth. United States Department of Agriculture, June 2004. http://dx.doi.org/10.32747/2004.7586471.bard.
Full textAbstract:
The original objectives were: A. To determine the critical embryonic age for monochromatic green light stimulation. B. To follow the ontogeny of embryos exposed to monochromatic green light vs. darkness. C. To investigate the effects of monochromatic green light illumination on myoblast and fiber development in the embryo. D. To investigate the stimulatory effect of light combinations during embryo and post-hatch periods on growth and meat production. E. To evaluate the direct effect of monochromatic green light on cultured embryonic and adult myoblasts. The overall purpose of this study was to investigate the effect of monochromatic light stimuli during incubation period of broilers on muscle development and satellite cell myogenesis. Based on previous studies (Halevy et al., 1998; Rozenboim et al., 1999) that demonstrated the positive effects of green-light illumination on body and muscle growth, we hypothesized that monochromatic light illumination accelerates embryo and muscle development and subsequently enhances muscle growth and meat production. Thus, further decreases management costs. Under the cooperation of the laboratories at the Hebrew University of Jerusalem and University of Washington we have conducted the following: 1. We have established the critical stage for exposure to green monochromatic light which has the maximal effect on body and muscle growth (Objective A). We report that embryonic day 5 is optimal for starting illumination. The optimal regime of lighting that will eliminate possible heat effects was evaluated by monitoring egg core temperature at various illumination periods. We found that intermitted lighting (15 min. on; 15 min. off) is optimal to avoid heat effects. 2. We have evaluated in detail gross changes in embryo development profile associated to green light stimuli vs. darkness. In addition, we have investigated the stimulatory effect of light combinations during embryo and post-hatch periods on body and muscle growth (Objective B,D). 3. We have studied the expression profile of muscle regulatory proteins during chicken muscle cell differentiation in cultures using newly developed antibodies. This study paved the way for analyzing the expression of these proteins in our photo stimulation experiments (Objective C). 4. We have studied the pattern ofPax7 expression during myogenesis in the posthatch chicken. Experimental chick pectoralis muscles as well adult myoblast cultures were used in this study and the results led us to propose a novel model for satellite cell differentiation and renewal. 5. The effects of monochromatic green light illumination during embryogenesis have been studied. These studies focused on fetal myoblast and satellite cell proliferation and differentiation at pre- and posthatch periods and on the effects on the expression of muscle regulatory proteins which are involved in these processes. In addition, we have analyzed the effect of photo stimulation in the embryo on myofiber development at early posthatch (Objective C). 6. In follow the reviewers' comments we have not conducted Objective E. The information gathered from these studies is of utmost importance both, for understanding the molecular basis of muscle development in the posthatch chicks and for applied approach for future broiler management. Therefore, the information could be beneficial to agriculture in the short term on the one hand and to future studies on chick muscle development in the embryo and posthatch on the other hand.
6
Erdman, Richard, Geoffrey Dahl, Hanina Barash, Israel Bruckental, Avi Shamay, and Anthony Capuco. Management Strategies to Maximize Skeletal Growth Rate in Dairy Heifers. United States Department of Agriculture, July 2002. http://dx.doi.org/10.32747/2002.7695848.bard.
Full textAbstract:
The objectives of this study were to determine the effects of recombinant bovine somatotropin (bST) and added dietary rumen undegradable protein (RUP) on organ and tissue weights and body composition in growing dairy heifers. A total of 32 Holstein heifers, 3 months of age at the beginning of the study were used in the experiment. Eight heifers were slaughtered at 3 mo of age to determine pre- treatment body composition. The remaining heifers were randomly assigned to treatments (n=6) consisting of 0.1 mg/kg body weight per day of bST and 2% added dietary RUP (dry matter basis) applied in a 2X2 factorial design. A total of six heifers per treatment group (3 each at 5 and 10 mo of age), were slaughtered to determine body composition an organ masses. There was a trend for increased live and empty body weights (EB:W), carcass and non-carcass components for heifers treated with bST or fed RUP. Added RUP increased rumen and reticulum weights whereas administration of bST tended to increase the weights of small and large intestine at 10 months of age by 22 % and 26%, respectively. Spleen, heart, and kidney weights at 10 months of age were increased 36%, 28% and 23% for bST treatments respectively, compared with controls. Rates of ash and protein deposition between 3 and 10 months of age were increased by bST by 7.2 g/d and 28.9 g/d, respectively, while no treatment differences were observed for rates of fat and energy deposition. Bovine somatotropin significantly altered the metabolism of growing heifers in a manner that led to increased protein and ash deposition, and tended to reduce fat percentage, and there was a similar tendency observed with added RUP. This suggests that nutritional and endocrine manipulations could increase growth rates of skeletal and lean tissues without increasing fat deposition in prepubertal dairy heifers.
7
Wyndham, Amber, Emile Elias, Joel R. Brown, Michael A. Wilson, and Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands in Southeast Arizona and Southwest New Mexico’s Major Land Resource Area 41. United States. Department of Agriculture. Southwest Climate Hub, August 2018. http://dx.doi.org/10.32747/2018.6818230.ch.
Full textAbstract:
Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altered species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates and/or a change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state-and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are necessary at the local level to inform local management decisions and help to ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and the Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level: it is based on ESs/STMs that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and to support informed decision-making for selecting management adaptations within MLRA 41.
8
Wyndham, Amber, Emile Elias, Joel R. Brown, Michael A. Wilson, and Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands of Southeastern Colorado’s Major Land Resource Area 69. United States. Department of Agriculture. Southwest Climate Hub, January 2018. http://dx.doi.org/10.32747/2018.6876399.ch.
Full textAbstract:
Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability resulting in decreased plant productivity and altering species composition which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates, change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state and transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending on geographic location. Vulnerability assessments and adaptation strategies are needed at the local level to inform local management decisions and help ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level based on ESs/STMs that will help landowners and government agencies identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and support informed decision-making for selecting management adaptations within MLRA 69.
9
Wyndham, Amber, Emile Elias, Joel Brown, Michael Wilson, and Albert Rango Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands in Southeast Arizona and Southwest New Mexico’s Major Land Resource Area 41. USDA Southwest Climate Hub, August 2018. http://dx.doi.org/10.32747/2018.6947060.ch.
Full textAbstract:
Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altered species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates and/or a change in livestock breeds and/or grazing
practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state-and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are necessary at the local level to inform local management decisions and help to ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and the Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the
Major Land Resource Area (MLRA) level: it is based on ESs/STMs that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and to support informed decision-making for selecting management adaptations within MLRA 41.
10
Wyndham, Amber, Emile Elias, Joel Brown, Michael Wilson, and Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands of Southeastern Colorado’s Major Land Resource Area 69. USDA Southwest Climate Hub, July 2018. http://dx.doi.org/10.32747/2018.6947062.ch.
Full textAbstract:
Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altering species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates, change in livestock breeds and/or grazing practices
are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites and their associated state–and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are needed at the local level to inform local management decisions and help ameliorate the effects of climate change on rangelands. The United States Department of Agriculture (USDA) Southwest Climate Hub and Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability
assessment at the Major Land Resource Area (MLRA) level, based on ecological sites and state-and-transition models that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and support informed decision-making for the selection of management adaptations within MLRA 69.