Thermal Management of Transient Power Spikes in Electronics - Phase Change Energy Storage or Copper Heat Sinks?

A transient thermal analysis is performed to investigate thermal control of power semiconductors using phase change materials, and to compare the performance of this approach to that of copper heat sinks. Both the melting of the phase change material under a transient power spike input, as well as the resolidification process, are considered. Phase change materials of different kinds (paraffin waxes and metallic alloys) are considered, with and without the use of thermal conductivity enhancers. Simple expressions for the melt depth, melting time and temperature distribution are presented in terms of the dimensions of the heat sink and the thermophysical properties of the phase change material, to aid in the design of passive thermal control systems. The simplified analytical expressions are verified against numerical simulations, and are shown to be excellent tools for design calculations. The suppression of junction temperatures achieved by the use of phase change materials when compared to the performance with copper heat sinks is illustrated. Merits of employing phase change materials for pulsed power electronics cooling applications are discussed

Wide parameter search for isolated pulsars using the Hough transform

We use the Hough transform to analyze data from the second science run of the LIGO interferometers, to look for gravitational waves from isolated pulsars. We search over the whole sky and over a large range of frequencies and spin-down parameters. Our search method is based on the Hough transform, which is a semi-coherent, computationally efficient, and robust pattern recognition technique. We also present a validation of the search pipeline using hardware signal injections.Comment: Presented at GWDAW-9 in Annecy, France (Dec. 2004). 11 pages, 5 Figures. To appear in Classical and Quantum Gravit

Failure of Aileron Control Cable in Ajeet Aircraft MK-E-2015

The Aileron control cable of an Ajeet aircraft was found snapped . On ootical and scanning electron microscopic examination, it was found that the majority of the strands of the cable had thinned due to excessive contact wear with a oulley and subsequently failed in tension

Immunology of occupational lung diseases caused by dust: an overview

The lungs are exposed to numerous injurious substances.Such injury may be the result of immunological or non-immunological mechanisms. The lung clears itself of inhaled particles by means of ciliated cells lining the airways and the macrophages.The latter play an important role in the immune process as well.Inorganic particles are ingested by macrophages and if found inert are transported for eventual expulsion.Particles such as silica are poorly handled by macrophages, they not only damage the macrophages but also impair their function. Others, such as asbestos, may stimulate fibrosis. Endogenous factors such as the presence of auto-antibodies (rheumatoid factor or anti-nuclear factor) alter the response of the host to inhaled particles.The pathological changes caused by handling inorganic dusts include intestitial fibrosis, nodular fibrosis or macule formation leading to emphysema.Occupational asthma a occurs when individuals are exposed to dusts during the course of their work. The lung responds differently to organic dust. T cells and complement are important elements in handling organic dust.The role of inhaled steroids which have no significant systemic effects in the prevention of certain occupational asthmas is worth evaluating, apart from control measures which minimise the exposure

ClimateNLP: Analyzing Public Sentiment Towards Climate Change Using Natural Language Processing

Climate change's impact on human health poses unprecedented and diverse challenges. Unless proactive measures based on solid evidence are implemented, these threats will likely escalate and continue to endanger human well-being. The escalating advancements in information and communication technologies have facilitated the widespread availability and utilization of social media platforms. Individuals utilize platforms such as Twitter and Facebook to express their opinions, thoughts, and critiques on diverse subjects, encompassing the pressing issue of climate change. The proliferation of climate change-related content on social media necessitates comprehensive analysis to glean meaningful insights. This paper employs natural language processing (NLP) techniques to analyze climate change discourse and quantify the sentiment of climate change-related tweets. We use ClimateBERT, a pretrained model fine-tuned specifically for the climate change domain. The objective is to discern the sentiment individuals express and uncover patterns in public opinion concerning climate change. Analyzing tweet sentiments allows a deeper comprehension of public perceptions, concerns, and emotions about this critical global challenge. The findings from this experiment unearth valuable insights into public sentiment and the entities associated with climate change discourse. Policymakers, researchers, and organizations can leverage such analyses to understand public perceptions, identify influential actors, and devise informed strategies to address climate change challenges

A group theoretic approach to detecting gravitational waves from asymmetric rotating neutron stars

The era of advanced ground based interferometric detectors of gravitational waves (GW) has arrived. These detectors are expected to go line in six years or so from now and which will have requisite sensitivity for detect- ing and observing astrophysical gravitational wave sources. In this article we will focus on a specific GW source, the GWs emitted by an isolated rotating neutron star/pulsar, and describe a novel approach to address this highly computationally intensive problem. We will describe how the symmetries in the model can be potentially used to reduce the computational effort

Synthesis of polythiophene n-type and p-type doping and compensation

The synthesis of pdythiophene leading to the formation of n-type potythiophene, p-type polythiophene and neutral polythiophene has been investigated through electropolymerization with different dopant ions. The influence of doping level over conductivity of the polymer matrix has also been studied which reveals that a preselected room temperature conductivity can easily be imparted to the parent polymer chain. It has also been found that the compensation of one type of conductivity over other occurs during the process of dedoping and redopin

Estrogen receptor-Sp1 complexes mediate estrogen-induced cathepsin D gene expression in MCF-7 human breast cancer cells

Cathepsin D is an estrogen (17 beta-estradiol, E2)-inducible lysosomal protease. A putative estrogen receptor (ER)-Sp1-like sequence (GGGCGG(n)23ACGGG) has been identified in the non-coding strand of the cathepsin D promoter (-199 to -165), and electromobility shift assays of nuclear extracts from MCF-7 and HeLa cells confirm that both the ER and Sp1 protein bind to 32P-labeled ER/Sp1 oligo. For example, nuclear extracts from MCF-7 cells bind to the 32P-labeled ER/Sp1 oligo; however, ER/Sp1 binding can be decreased by selective competition with excess unlabeled estrogen responsive element and Sp1 oligos, immunodepletion with ER or Sp1 antibodies, and by treating cells with ICI 164,384, an antiestrogen which inhibits formation of ER homodimer. Moreover, E2-induced chloramphenicol acetyltransferase (CAT) activity in MCF-7 cells cotransfected with a human estrogen receptor expression plasmid and a plasmid containing an ER/Sp1 sequence cloned upstream to a thymidine kinase promoter and a CAT reporter. In cotreatment studies, ICI 164,384 inhibited E2-induced CAT activity. In contrast, E2 did not induce CAT activity in MCF-7 cells transfected with plasmids containing mutations in the ER or Sp1 segments of the ER/Sp1 oligo, thus confirming that both cognate binding sites are required for estrogen responsiveness

Dynamic Development Contests

Public, private, and not-for-profit organizations find advanced technology and product development projects challenging to manage due to the time and budget pressures, and turn to their development partners and suppliers to address their development needs. We study how dynamic development contests with enriched rank-based incentives and carefully-tailored information design can help these organizations outsource their development projects at the minimum project lead time by stimulating competition among suppliers. We show that an organization can use dynamically adjusted flexible rewards to achieve the absolute minimum expected project lead time at a significantly lower cost than a fixed-reward policy. Importantly, our flexible-reward policy pays the absolute minimum expected reward (i.e., achieves the first best). We further study the case where the organization does not have sufficient budget to offer a reward that attains the absolute minimum expected lead time. We propose that in this case, the organization can dynamically increase the contest reward until its budget constraint binds and then use information sharing as a strategic tool to incentivize suppliers. Specifically, we propose an easy-to-implement random-update policy where the organization periodically monitors the status of suppliers at random times and immediately discloses any partial progress. We show that such a random-update policy outperforms other canonical information disclosure strategies. Our results indicate that dynamic rewards and strategic information disclosure are powerful tools to help organizations outsource their development needs swiftly and cost effectively