Design,development and testing of a novel non-tracking solar cooker

A novel solar cooker that does not require any tracking, has been designed, fabricated and tested and its performance has been compared with the hot-box solar cooker. The performance of the novel solar cooker is almost similar with the hot-box solar cooker though it is kept fixed while the hot box is tracked towards the sun every hour. The overall efficiency of the novel solar cooker has been found to be 29·5%. The payback period varies between 1·30 and 3·29 years depending upon the fuel it replaces. The payback periods are in the increasing order with respect to fuels such as firewood, coal, electricity, kerosene and LPG. The short payback period shows that the use of the novel non-tracking solar cooker is economical. © 1998 John Wiley & Sons, Ltd.     

Assessment of a capability index sensitive to skewness

For many quality characteristics, such as circularity, cylindricity, straightness and flatness, positive skewness in the inspection data is the norm, and, in fact, is desirable. Summarizing the process performance using such data in conjunction with capability indices has recently received a considerable amount of attention, with new indices being proposed and compared for usefulness and accuracy. This paper is intended to contribute to this growing discussion, and to add a unique focus. In particular, this investigation concentrates on one form of a neoclassical index, the Cs index, originally proposed to be sensitive to skewness and to decrease in value as the skewness increased in the underlying distribution of the data. In other words, ‘skewness is badness’. Looking at this index from an altered perspective, the possibility that this index could serve a useful purpose in summarizing process performance for such non‐normal processes by merely changing its interpretation or slightly changing its form is considered. Hence, actual data from circularity measurements are used to identify a relevant group of distributions, and then the accuracy of C_s is investigated along with its modified version for this group of distributions. In particular, this investigation includes several Rayleigh and gamma distributions for various sample sizes and reports on the bias of the proposed estimators. These findings indicate that such a modified index has some useful attributes in reflecting process performance, with respect to the percentage of non‐conformance and the accuracy for relatively large samples. Copyright © 2001 John Wiley & Sons, Ltd.     

A Cu-Al2O3-Al moisture sensor for high humidities

A novel humidity sensor using the structure Cu-Al₂O₃-Al has been developed for high humidity applications. The capacitance and conductance characteristics of the sensor, measured as a function of humidity at different frequencies, are given. The temporal drift in the characteristics is also investigated. A theory describing the operational behaviour of this device is proposed based on the humidity-sensitive spreading conductance of the oxidised copper film. This ingenious technique has a remarkable multiplicative action on the high humidity sensitivity.     

A distributed resource management model for Virtual Private Networks: Tit-for-Tat strategies

In this paper, we address the autonomic resource management problem for Virtual Private Networks (VPNs) in the presence of stochastic and selfish VPN operators. Resource management is one of the most important problems that faces Internet Service Providers. In the literature, the Autonomic Service Architecture is proposed to provide a resource management model that allows systems to manage themselves and aiming to utilize optimally the unused resources. Unfortunately, this model suffers from two major limitations. First, unused resources from underloaded VPNs (lenders) are utilized over the overloaded ones (borrowers) without considering the unexpected changes of the VPNs’ state, which may often happen in the case of multimedia transmissions. This may affect negatively the Quality-of-Service (QoS) of the lenders while improving the QoS of the borrowers. Second, underloaded VPNs’ operators might behave selfishly and refuse to lend their unused (spare) resources to other overloaded VPNs. To overcome these limitations, we propose a distributed autonomic resource management, which is modeled as a repeated non-cooperative game with stochastic and selfish players. The classical Tit-for-Tat strategy is modified to cope with VPN operators who are not always able to lend some resources to others. Four different strategies are derived from Tit-for-Tat to motivate VPN operators to lend their resources to others. As far as we know, our work is among the first efforts that uses repeated non-cooperative game theory to motivate selfish participants to cooperate and to distinguish between stochastic and purely selfish VPNs’ operators. In our setting, this results in cooperative sharing of unused resources among VPNs. Simulation results show that Tit-for-Tat strategy leads to deadlocks, while our strategies assure good gains to cooperative VPN operators and punish the selfish ones.     

Study of the effect of thermal annealing on high k hafnium oxide thin film structure and electrical properties of MOS and MIM devices

The effect of rapid thermal annealing on structural and electrical properties of high k HfO₂ thin films is investigated. The films were initially deposited at pre-optimized sputtering voltage of 0.8 kV and substrate bias of 80 V in order to get optimized results for oxide charges and leakage current as a MOS device. The film properties were investigated for optimum annealing temperature in oxygen and optimum rapid thermal annealing temperature in nitrogen respectively to get the best electrical results as a MOS device structure. The film thickness, composition and microstructure is studied by Laser Ellipsometry, XRD and AFM and the effect of thermal annealing is shown. The electrical I–V and C–V characteristics of the annealed dielectric film were investigated employing Al-HfO₂-Si MOS capacitor structure. The flat-band voltage (V _fb) and oxide-charge density (Q _ox) were extracted from the high-frequency C–V curve. Dielectric study were further carried out on HfO₂ thin films having metal–insulator–metal (MIM) configuration over a wide temperature (300–500 K) and frequency (100 Hz to 1 MHz) range.     

Regression of metastatic liver tumors in rats treated with angiogenesis inhibitor TNP-470: occurrence of apoptosis and necrosis

To clarify the mechanism of the reduction of metastatic liver tumors in rats treated with angiogenesis inhibitor TNP-470, the death of tumor cells was examined pathologically and ultrastructurally. Liver metastases were developed by intravenous injection of AH-130 cells. TNP-470 was given subcutaneously after tumor cell injection. Alterations in the size and number of metastatic tumors were examined at various time points, in association with the analysis of cell death pattern. The metastatic nodules were divided into 4 groups according to the morphological patterns of cell death; no cell death, scattered apoptosis, central necrosis, and diffuse necrosis. The number and size of the metastatic tumors at 2 weeks in untreated rats were larger than those in treated rats. The number of tumors in untreated rats decreased, but the tumor size increased. All rats treated with TNP-470 were alive and free from tumors after 4 weeks, whereas all the untreated rats died of liver metastases. The percentages of the tumors with necrosis in untreated rats (61.2% at 2 weeks and 100% at 4 weeks) were significantly higher than that (31.8% at 2 weeks) in treated rats (P < 0.01). The percentage of the tumors containing apoptotic cells in treated rats was significantly higher than that in untreated rats (54.5% vs. 30.6%; P < 0.05). The growth of metastatic tumors without treatment might be faster than the growth of vessels in untreated tumors, resulting in central necrosis due to ischemia. On the other hand, the reduction of metastatic liver tumors treated with TNP-470 might be caused by inhibition of angiogenesis, providing a weak ischemic stimulus which triggers apoptosis, rather than by a direct cytotoxic effect on tumor cells, because previous in vivo experiments demonstrated that TNP-470 affected endothelial cells but not tumor cells.     

Contact resistance characteristics of the low cost CuNiCr thin film resistor system

In this paper an investigation of the use of copper as a contact and interconnecting material for thin film resistors and hybrid circuits is reported. The current-voltage characteristics of Nichrome thin film resistors with copper contacts and the contact resistance of $\text{Cu}\text{NiCr}$ metallizations were measured. The effect of thermal annealing on the contact characteristics was also studied.     

Untersuchungen über die Entstehung von Kohlenwasserstoffen in erhitzten gesättigten Fettsäuren und Fettsäureestern

Studies on the Formation of Hydrocarbons in Fatty Acids and Fatty Acid Esters on Heating The investigations on the volatile compounds of the unsaponifiable matter and the steam distillate of heated saturated fatty acids have shown that on heating in the presence of air, along with other substances, hydrocarbons having a chain length 1 to 2 C atoms shorter than the corresponding fatty acids are formed. The splitting proceeds so slowly in the case of esters that even after 4 hrs of heating at 160°C no reaction products could be detected. By heating palmitic acid under the same conditions, except that vacuum was employed, no perceptible quantities of hydrocarbons were found.     

Study of hafnium oxide deposited using Dense Plasma Focus machine for film structure and electrical properties as a MOS device

The electrical properties of HfO₂ gate dielectric as a MOS structure deposited using Dense Plasma Focus (DPF) device under different ambient gases were investigated. DPF is unique machine used for the first time to fabricate a MOS device as it can be used to deposit dielectric film in one shot and can also be used to change the properties of the thin film surface. The films were first deposited under pre-optimized conditions of DPF device to have best focus for producing ions. The substrate for deposition of dielectric material was placed at a distance of 5 cm from the focus under argon ambient and then under nitrogen ambient. The I-V, C-V characteristics of the dielectric film were investigated employing Al-HfO₂-Si MOS capacitor structure deposited using DPF. The MOS devices were studied to determine electrical parameters like breakdown voltage, oxide charges and leakage current deposited under two different gas ambient. The microstructure of thin film is examined by using AFM and the thickness of the film is examined using an ellipsometer. The reduction in surface roughness, shift in Flat-band voltage (V_fb) and reduction in oxide-charge density (Q_ox) is seen maximum for MOS capacitor where HfO₂ as gate dielectric is deposited under nitrogen ambient using DPF machine.     

Performance and testing of large-size solar water heater cum solar cooker

The performance of a novel device has been tested. The device can be used as a collector cum storage type solar water heater during the winter, and, with minor adjustments, it can be used as a hot-box solar cooker. The device can provide hot water at 50–60°C in the evening, which can be maintained at 40–45°C until the following morning. It can also be used for cooking food for about 40 people. The efficiencies of the device as a solar water heater and as a solar cooker have been found to be 67.7% and 29.8%, respectively. The payback period varies between 1.64 to 5.90 years depending on the fuel it replaces. The payback periods are of increasing length with respect to the fuels firewood, coal, electricity, LPG and kerosene.