A Temperature Analysis of High-power AlGaN/GaN HEMTs

Galliumnitride has become a strategic superior material for space, defense and civil applications, primarily for power amplification at RF and mm-wave frequencies. For AlGaN/GaN high electron mobility transistors (HEMT), an outstanding performance combined together with low cost and high flexibility can be obtained using a System-in-a-Package (SIP) approach. Since thermal management is extremely important for these high power applications, a hybrid integration of the HEMT onto an AlN carrier substrate is proposed. In this study we investigate the temperature performance for AlGaN/GaN HEMTs integrated onto AlN using flip-chip mounting. Therefore, we use thermal simulations in combination with experimental results using micro-Raman spectroscopy and electrical dc-analysis.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Searching for thermal signatures of persistent currents in normal metal rings

We introduce a calorimetric approach to probe persistent currents in normal metal rings. The heat capacity of a large ensemble of silver rings is measured by nanocalorimetry under a varying magnetic field at different temperatures (60 mK, 100 mK and 150 mK). Periodic oscillations versus magnetic field are detected in the phase signal of the temperature oscillations, though not in the amplitude (both of them directly linked to the heat capacity). The period of these oscillations ($\Phi_0/2$, with $\Phi_0 = h/e$ the magnetic flux quantum) and their evolution with temperature are in agreement with theoretical predictions. In contrast, the amplitude of the corresponding heat capacity oscillations (several $k_{\mathrm{B}}$) is two orders of magnitude larger than predicted by theory

Applying theory of constraints to timber harvesting: A case study from the Northeast USA

Logging firms are a critical link in wood supply chains, connecting forest landowners with markets for wood products. Improving operational planning can benefit individual logging firms as well as the larger wood supply chain in which they operate. Applying concepts from Theory of Constraints (TOC) to timber harvesting may help achieve greater predictability and efficiency when planning harvest operations. However, examples that demonstrate how TOC can improve logging operations are lacking. This study focuses on the analysis of production and activity data collected during the harvest of a temperate mixed hardwood forest in the Northeast United States using a chainsaw-forwarder system through a TOC lens. Specifically, the drum-buffer-rope (DBR) method was used to reschedule operator and machine activities such that a consistent flow of wood from stump to landing was maintained despite anticipated production setbacks. The results of this case study provide insights into the usefulness of applying TOC to logging operations. In particular, logging businesses must be able to estimate machine and operator productivity within a given harvest context to identify and exploit system constraints, while taking full advantage of unused capacity of any non-constraint functions

Needs Assessment Surveys: Do They Predict Attendance at Continuing Education Workshops?

Extension educators regularly conduct needs assessment surveys to identify their clients\u27 education preferences. This study compared data from a continuing education needs assessment survey of NYS forest resource managers with attendance records from workshops to learn if survey respondents attended programs that they indicated a preference for. Our findings suggest that, although educators can rely on these surveys to assess program feasibility, only a small percentage of survey respondents who indicate an interest in a topic will actually attend a program on that topic. Our results illustrate why educators should consider using additional tools to assess their clients\u27 education needs

The Constitution Commandeth: Thou Shalt Not Protect the Same Subject Matter Under Design Patent and Trade Dress Laws

For many years and still currently, it has been assumed—and even expressly asserted—that it is perfectly permissible to “stack” various legal theories (concurrently or consecutively) to protect nonfunctional “designs” for products. This is despite infrequent but cogent arguments that the available theories, notably design patents and product design trade dress—both of which are based upon federal statutes—are not Constitutionally compatible due to at least the concept of Superfluity. The authors of this article carefully examine the origin, nature, and meaning of these two types of IP protections in the context of their two Constitutional bases—the Patent/Copyright Clause and the Commerce Clause—and conclude that, indeed, “stacked” protections are not Constitutionally permissible; the authors then recommend a workable solution which they dub, the “Kewanee Kompromise.

Applying Theory of Constraints to Timber Harvesting: A Case Study from the Northeast USA

Logging firms are a critical link in wood supply chains, connecting forest landowners with markets for wood products. Improving operational planning can benefit individual logging firms as well as the larger wood supply chain in which they operate. Applying concepts from Theory of Constraints (TOC) to timber harvesting may help achieve greater predictability and efficiency when planning harvest operations. However, examples that demonstrate how TOC can improve logging operations are lacking. This study focuses on the analysis of production and activity data collected during the harvest of a temperate mixed hardwood forest in the Northeast United States using a chainsaw-forwarder system through a TOC lens. Specifically, the drum-buffer-rope (DBR) method was used to reschedule operator and machine activities such that a consistent flow of wood from stump to landing was maintained despite anticipated production setbacks. The results of this case study provide insights into the usefulness of applying TOC to logging operations. In particular, logging businesses must be able to estimate machine and operator productivity within a given harvest context to identify and exploit system constraints, while taking full advantage of unused capacity of any non-constraint functions

The New York City Watershed Model Forests Revisited Five Years Later: An Assessment of Successes, Failures, and Challenges for the Future

The New York City Watershed Model Forests were established to demonstrate that working forested landscapes can be compatible with water quality. The Model Forests were designed to integrate education, research, and demonstration to a wide audience. Two of the four Model Forests are successful, serving the outreach and continuing education needs of forest stewards in the watershed. The other two Model Forests have confronted challenges stemming from the negative public perception of forest management. Explanations on successes and shortcomings, coupled with a survey analysis of model forest users, provide insight into the project\u27s progression over the last 7 years

Does Landowner Awareness and Knowledge Lead to Sustainable Forest Management? A Vermont Case Study

Family forest owners control 40% of forestland in the United States. Timber harvesting on family forests represents a critical component of the nation\u27s wood supply. We examined how awareness and knowledge translated into actual forest management practices. We conducted field surveys on 59 family forest properties, coupled with a landowner survey designed to measure landowner engagement. We determined that engaged landowners implemented silviculture and Best Management Practices at a higher level than their less engaged counterparts. Improvement was needed across the board. Forestry Extension professionals should continue to promote and re-enforce awareness and knowledge among landowners