Economics of liquid hydrogen from water electrolysis

Using the data from vendors and open literature, we have constructed a preliminary cost model to predict the cost of liquid hydrogen (LH₂) from water electrolysis. The model has been applied to two LH₂ plants. Both have a production rate of 10 886 kg day⁻¹. The first plant (Plant 1) consists of a tank-type electrolyzer and a liquefier and runs all day at the base-load (or equivalent base-load) power rate. The second (Plant 2) consists of a tank-type electrolyzer, a liquefier, a compressor, and storage vessels. The electrolyzer and the compressor shall run only during the off-peak hours at the off-peak power rate. However, the liquefier shall run all day at the base-load (or equivalent base-load) power rate. The costs of LH₂ from both plants are presented. Unless the base-load power rate is high and the off-peak power rate is substantially low, Plant 1 appears to be economically more feasible than Plant 2.     

An empirical formula for the prediction of rain attenuation infrequency range 0.6 - 100 GHz

An empirical formula for calculating the extinction cross section (ECS) by raindrops over a broad frequency range is first derived based on extensive calculations made on a widely varying in mean radius of modified Pruppacher and Pitter (MPP) raindrop models ranging from 0.25 to 3.5 mm. The expansion coefficients in the empirical formula are determined by least-squares curve fitting of numerical data obtained by the volume integral equation formulation (VIEF). The formula satisfies the frequency and raindrop size dependence. Numerical results obtained from the empirical formula for calculating the ECS are generally in good agreement with those calculated by the VIEF for raindrops with mean radius varying from 0.25 to 3.5 mm in the frequency range from 0.6 to 100 GHz. The average error in the ECS is less than 10%. The formula thus provides a simple and inexpensive method for calculating the ECS of raindrops, which otherwise requires complicated and expensive methods of calculation. By implementing this empirical formula of ECS into the rain attenuation equation, a new numerically empirical formula for calculating the specific rain attenuation is also proposed. The validity of the empirical formula for calculating the specific rain attenuation is also checked by comparing the obtained results of specific rain attenuation with those obtained from Li et al.'s (1995) solution, Yeo et al.'s (1993) measurement, and Olsen et al.'s (1978) power-law equation     

我国建筑涂料技术进步简评

从以下诸方面简述我国建筑涂料的技术进步:⑴新品种涂料的研制开发;⑵加强对配套材料及施工技术的研究;⑶超细填料在涂料中的应用;⑷计算机自动配色技术;⑸产品标准的修订;⑹建筑涂料的实用范围扩大。     

Efficient design/simulation algorithms for simultaneous switching noise in leadframe packages

 Two new modeling and simulation approaches for Simultaneous Switching Noise (SSN) are described and compared to “brute force” simulation by SPICE. Both simulation accuracy and simulation run-time are considered. The two new approaches are: 1) the “effective inductance” method, in which an approximate, very efficient method of extracting an SSN L _eff  is utilized; and 2) the “macromodel” method, in which the complex inductance network responsible for SSN is represented by only a few dominant poles in the frequency domain and the time domain response is obtained by an efficient convolution algorithm. Both approaches are shown to be accurate and fast, but only the effective inductance algorithm is robust in numerical convergence. Received: 19 March 1997 / Accepted: 25 March 1997     

A simple method for extracting average doping concentration in thepolysilicon and silicon surface layer near the oxide in polysilicon-gateMOS structures

The author demonstrates a simple technique that extracts average doping concentration in the polysilicon and silicon near the oxide in a metal/polysilicon/oxide/silicon system. The technique is based on the maximum-minimum capacitance method on two large area structures-one MOSFET and one MOSC (MOS capacitor). The technique is simple and reliable since only three data points in the C-V data are required-two points in MOSC C-V and one point in MOSFET C-V. The technique avoids inaccuracy caused by interface traps at the polysilicon/oxide and the oxide/silicon interface. The technique can be implemented into fab routine electric-test procedures for simultaneously monitoring change of doping concentration in polysilicon and silicon during process development     

Enhancement of oxide break-up by implantation of fluorine inpoly-Si emitter contacted p+-n shallow junctionformation

In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p⁺-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900°C. As a result, the junction depth of the BF₂-implanted device is much larger than that of the boron-implanted device     

稀土在搪瓷面釉上应用的研究

采用稀土氧化物和无机化合物的复合物（不简称ＲＩ－复合物）作为搪瓷釉浆悬浮剂，使之全部或大部分代替粘土，进行了一系列试验，已获得成功，突破了长期来搪瓷工业离不开粘土的传统工艺，并实现了工业化生产。     

Effects of thymectomy and glucocorticoid therapy on peripheral lymphocytes in myasthenia gravis

Clinical manifestations and peripheral blood lymphocyte subset changes were studied in patients with myasthenia gravis (MG) to elucidate the mechanism of clinical improvement following treatment, with thymectomy (Tx) or glucocorticoid (GC) therapy. The changes found were: 1. There was a significant increase in percentages of CD3+, CD29+ CD4+ cells and CD4/CD8 ratio and a significant decrease in percentages of CD8+ and CD16,56+ cells in patients who had never been treated with any immune therapy. 2. After Tx or GC therapy, CD3+ and CD4+, CD29+ cells were decreased, but the number CD19+ and CD16, CD56 cells did not change. 3. Tx had a special effect on CD8+ cells. In most of the patients who showed clinical improvement after Tx, CD8+ cells were increased and CD4/CD8 ratio wad decreased. 4. Anti-acetylcholine receptor (AChRAb) titers were markedly decreased after GC therapy. These results indicate that there were obvious abnormalities in cell-mediated immunity in addition to those in humoral immunity in myasthenia gravis. These abnormalities tended to be normalized after Tx or GC therapy.     

Hypergonadotropic secondary amenorrhea: clinical analysis of 126 cases

OBJECTIVE: To study the etiology and early diagnosis of hypergonadotropic amenorrhea and to explore the appropriate treatment for preserving their reproductive function. METHODS: 126 cases of secondary amenorrhea with serum follicular stimulating hormone (FSH) levels > or = 40 IU/I, were analysed. Their clinical manifestations, karyotypes, ovarian morphology and histology, reproductive hormone assays, and responses to estrogen therapy and ovulation induction were studied. RESULTS: 6 cases presented with histories of ovarian surgery, radiotherapy or chemotherapy. Among the other 120 cases, 18 manifested amenorrhea before or at 25 years of age, 102 developed amenorrhea after age 25. In the former group, 16 (88.9%) showed unilateral or bilateral gonadal dysgenesis, and the other 2(11.1%) were defined as resistant ovaries. Abnormalities of sex chromosome karyotype occurred in 44.4% (8/ 18). In the latter group, 68 underwent laparotomy or laparoscopy examination. Morphological and histological examinations of both ovaries showed atrophic ovaries in all cases accompanied by 30.9% (21/ 68) unilateral gonadal dysgenesis; sex chromosomal abnormality was found in only one with no sexual immaturation. The efficacy of estrogen treatment was significantly better among cases with amenorrhea less than 1 year as compared with those longer than 1 year. Clomiphene challenge test given to 8 cases during their irregular menstrual stages produced an elevation of FSH levels to > 20 IU/I. without any response of estradiol secretion. CONCLUSIONS: The earlier estrogen therapy is initiated, the greater possibility of pregnancy will be achieved in cases suffering from hypergonadotropic amenorrhea. The clomiphene challenge test may provide evidence of waning ovarian function for early diagnosis.