In-Situ monitoring of temperature and alloy composition of Hg1−xCdxTe using FTIR spectroscopic techniques

Optical real-time in-situ sensors play a very important role in the processing of semiconductor devices because of their noncontact remote nature and excellent compatibility with UHV systems. In this work, we report on progress in developing an in-situ temperature sensor for HgCdTe structures grown by molecular beam epitaxy (MBE). Based on the Fourier transform infrared (FTIR) spectrometer, this sensor is capable of continuous real-time monitoring of the surface temperature, thickness and alloy composition of HgCdTe epilayers. The accuracy and sensitivity of this FTIR technique were studied in all temperature ranges of interest. Also compared are two different methods of temperature determination obtained from the normalized spectral radiance. The influence of stray radiation and of sample holder rotation on the measurement accuracy have been studied. Reflectivity spectra for HgCdTe/CdZnTe(211) and HgCdTe/CdTe(211)/Si(211) structures have been analyzed in real time in order to determine the layer thickness and alloy composition for growing layers. Also discussed is a multilayer-structure optical model developed to solve the problem of composition determination at early stages of growth. The application of this model for fitting the transmission spectra is demonstrated.     

The Role of Intellectual Capital in Knowledge Transfer

The purpose of this study is to examine the roles of the three distinct aspects of intellectual capital, including human capital, organizational capital, and relational capital, in knowledge transfer. Regression analysis was used to test the hypotheses in a sample of 97 knowledge transfer cases. The results indicate that human capital and organizational capital are positively related to relational capital with partnering firms, which, in turn, has a positive effect on knowledge transfer performance. Our results provide evidences that relational capital plays a mediating role between human capital and organizational capital and knowledge transfer performance. The findings of this study contribute to the theoretical development of a conceptual model for explaining the interrelationships among three aspects of intellectual capital and knowledge transfer performance. The empirical evidences of the Sobel ( Sociological Methodology. San Francisco, CA: Jossey-Bass, 1982, pp. 290-312.) test in line with the Baron and Kenny's (J. Pers. Soc. Psychol. , vol. 51, pp. 1173-1182, 1986) procedure support the process-oriented view and indicate that relational capital would mediate the effects of human capital and organizational capital on knowledge transfer performance. The empirical evidences of this study fill the gap in the literature that is lack of empirical examination of the roles of intellectual capital in the knowledge transfer contexts. Managerial implications and future research directions are discussed.     

Novel impacts of glycol-modified poly(ethylene terephthalate)(PETG) to crystallization behavior of polyethylene naphthalate (PEN) within stretched miscible blends

For studied blends of amorphous glycol-modified poly(ethylene terephthalate) (PETG) and semicrystalline polyethylene naphthalate (PEN), melt miscibility is understood from the linear variation of a single glass transition temperature (T_g) over the entire composition range. The diluent effect of PETG component severely retarded the crystallization of PEN component within blends. Nevertheless, after being through isothermal stretching at 120 °C, crystallization was able to progress efficiently during heating in a continuous manner. Instead of being thermally relaxed back to amorphous state, parallel sliding motions of stretched PEN segments toward crystallization appear rather dominant. Within stretched blends, the PETG content emerged as a critical factor to the crystallinity increase of PEN fraction and the absence of lattice defect, instead of behaving as a diluent component. Furthermore, as being indicated by in-situ small-angle X-ray experiments, regular lamellar stacking gradually developed within stretched blends through heating, which indicates the involvement of thermally activated self-association of randomly distributed crystalline lamellae. With including a higher fraction of PETG component, these secondary ordering processes including lamellar thickening can be activated at lower temperature. Hence, the accompanied thermal relaxation of flexible PETG segment is inferred able to lubricate the sliding of stretched PEN segments in amorphous regions via lowering encountered frictional hindrance, and thus enhance both primary and secondary ordering processes within stretched blends.     

Statistical analysis and modeling of the temperature-dependent sleep behavior of drosophila

The sleep behavior of drosophila is analyzed under different temperatures. The activity per minute of the flies is recorded automatically. Sleep for a fruit fly is defined as the periods without any activity and longer than 5 minutes. Several parameters such as total sleep time, circadian sleep profile, quality of sleep are analyzed. The sleep behaviors are significantly different for flies at different temperature. Interestingly, the durations of daytime sleep periods show a common scale-free power law distribution. We propose a stochastic model to simulate the activities of the population of neurons which regulate the dynamics of sleep–wake process to explain the distribution of daytime sleep.     

Diagnosis of PTFE‐Nafion MEA degradation modes by an accelerated degradation technique

Cost and durability are central issues in the commercialization of proton‐exchange membrane fuel cells. This study used complex accelerated‐degradation protocols to diagnose the degradation modes of low‐cost polytetrafluoroethylene–Nafion membrane electrode assemblies (MEAs). Acceleration protocols included open‐circuit voltage, relative humidity cycling, and load cycling. Failure modes included measurements of cyclic voltammetry, linear sweep voltammetry, polarization curve, and AC impedance. The four modes (stages) of degradation were determined to be (i) catalyst aging, (ii) creep deformation, (iii) pinhole formation, and (iv) membrane failure. During catalyst aging, the maximum power density decreased by 0.117 mW cm^?2 cycle^?1. After the 280th cycle, creep deformation occurred, and the maximum power density decreased by 0.227 mW cm^?2 cycle^?1. Pinholes led to membrane failure and a final dramatic loss of performance (?0.453 mW cm^?2 cycle^?1). Therefore, membrane failure is the major factor in the failure of MEAs. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and Testing of an Energy Storage Material/Phase Change Material Enhanced Heat Sink

A concept of using energy storage material (ESM) or phase change material (PCM) to enhance the heat transfer dissipation by a conventional compact fin-based heat sink is demonstrated. An actual design is developed, fabricated, and tested to demonstrate the heat transfer enhancement. The heat sink is light weight (made with Aluminum) and miniature in size with a total fin length of 26 mm. Test results demonstrated that under a high peak load (4.4 W/cm²) and low duty power cycle (30/55 on/off ratio with a period of 85 sec), the peak temperature at the heating surface with the ESM/PCM heat sink is 5°C lower than that of a conventional heat sink. At the tip of the fin, the peak temperature with the ESM/PCM heat sink is 3°C lower than that of a conventional heat sink. When the external heat transfer coefficient increases (with increase air velocity), the impact of the PCM/ESM on the heat transfer performance is less. A numerical model, based on COMSOL, is developed to provide a theoretical understanding of the experimental observation.     

Construction rescheduling based on a manufacturing rescheduling framework

Changes during project execution frequently require schedule updating and rescheduling. However, few studies have discussed rescheduling issues or implemented rescheduling solutions for construction projects. This study investigates resource-constrained construction rescheduling issues using concepts associated with manufacturing rescheduling. Based on an initial schedule and actual progress, a novel rescheduling optimization model using Constraint Programming (CP) techniques is developed to reschedule projects. Two rescheduling methods: (1) complete regeneration (CR); and, (2) partial rescheduling (PR) while minimizing overall project variation are implemented in the proposed model to demonstrate the model capability and applications. PR requiring additional treatments to decrease overall project variation is performed using a novel constraint-release mechanism. Finally, using a case study, optimization results obtained using two rescheduling methods are analyzed and discussed.     

Geographic information system applied to measuring benthic environmental impact with chemical measures on mariculture at Penghu Islet in Taiwan

Cobia, Rachycentron canadum, is currently grown by marine aquaculture in Taiwan, particularly on Penghu Islet. Although the effect of marine aquaculture on the environment has been the subject of many studies, an understanding of its environmental impact has yet to be attained, and the continuing expansion of cage farming has caused noticeable ecological declines. Nevertheless, useful tools to measure this environmental degradation are scant. The results of this study suggest that the combination of a geographic information system (GIS) with redox potential and sulfide measurements can be used to definitively assess the condition of the benthic environment near cobia aquaculture sites and to help develop environmental monitoring programs. These applications could easily be adopted to assess multiple marine environmental conditions.     

Image Processing-Based Methodology for Optimizing Automotive Ignition Timing

Modern fuel-injected automobiles use an electronic engine control unit (ECU) that is programmed to ignite the air-fuel mixture in a way that maximizes the torque (TQ) and power output of the engine without compromising its reliability. The ECU achieves this by reading a base value from the primary ignition map (PIM) and then manipulating various other parameters to come up with the final solution. Each input into the final solution comes from a so-called map, which is a 3-D image that represents a set of all the possible values that each parameter can take on. In this paper, we develop a robust methodology using image processing techniques to optimize the PIM for automobiles. The techniques are used to compare, combine, manipulate, and reconstruct various maps. Experiments show that the process yields a gain of about 7 hp and a TQ of 15 ft middotlb measured at the wheels.