半干旱灌溉地区采用地下排水控制土地盐化的效果评价

一项大规模地下排水研究项目RAJAD（拉贾斯坦邦农业排水研究项目），在印度的拉贾斯坦邦实施，旨在控制因灌溉引起的土壤盐碱化问题。在12个野外试验地点获得了大量的地下排水数据。田间结果表明，地下排水系统对控制土壤盐碱化具有积极意义。广泛的监测结果显示，地下排水系统是控制土壤盐碱化的有效途径。试验数据表明，有地下排水系统的所有地区，其土壤盐化度都呈现出逐渐下降的趋势。土壤的脱盐速度在排水间距较小（〈40m）时比排水间距较大时（〉40m）要快。雨季通过地下排水系统淋洗排出的盐分数量大于灌溉季节引入的盐分数量。     

Optical Separation of Cells on Potential Energy Landscapes: Enhancement With Dielectric Tagging

We review the emergent techniques of microfluidic sorting of colloidal and cellular samples using optical forces. We distinguish between what we term as passive and active forms of particle sorting where we can sort either with the use of a fluorescent marker (active) or based on physical attributes alone (passive). We then examine cell sorting with optical potential landscapes such as a Bessel light beam and a multibeam interference pattern. For both forms of optical potential energy landscape, we further present the possibility of enhancing the optical sorting process by tagging dielectric microspheres onto the cells. The results suggest that the methodology of tagging can enhance the sorting of cells as they subsequently respond more strongly to an applied optical field or potential energy landscape. This technique presents a simple method to enhance the sorting process.     

An in-situ temperature measurement system for DUV lithography

Spatial uniformity of temperature across a silicon wafer is an important requirement during the post-exposure bake step of the deep-ultra-violet lithography process. Closed-loop temperature control provides a means by which the stringent temperature specifications can be achieved, provided that accurate feedback signal is available. As each new wafer is loaded for processing, its level of thermal contact with the temperature sensor may vary, leading to erroneous measurement of the wafer temperature. Such variation in thermal contact manifests itself as changes in the time constant of the sensor. This paper describes a method for in-situ estimation of the sensor parameters, and proposes an algorithm for post-processing the sensor output to improve measurement accuracy. Experimental results are presented to demonstrate the effectiveness of the algorithm in improving the accuracy of the feedback signal, thereby reducing the undesirable influence of poor thermal contact on the performance of the closed-loop temperature control system.     

Optimal control of a queueing system with two heterogeneous servers

The problem considered is that of optimally controlling a queueing system which consists of a common buffer or queue served by two servers. The arrivals to the buffer are Poisson and the servers are both exponential, but with different mean service times. It is shown that the optimal policy which minimizes the mean sojourn time of customers in the system is of threshold type. The faster server should be fed a customer from the buffer whenever it becomes available for service, but the slower server should be utilized if and only if the queue length exceeds a readily computed threshold value.     

Analysis of minimum clamping force

Our objective is to determine the minimum clamping force that keep the workpiece stable during the metal cutting process. In analyzing the stability of the workpiece, one usually proves that no instant center of motion can occur on the clamping plane. However, previous search algorithms for the instant center of motion either lack theoretical sufficiency or computational efficiency. This paper presents a new method derived from the correlation between cutting force and clamping moment. This method increases the search efficiency by pruning inadequate search directions. In addition, examples are provided to illustrate minimum clamping force analysis under different fixturing conditions.     

Bone mineral density and bone markers in relation to vitamin D receptor gene polymorphisms in Chinese men and women

Whether vitamin D receptor gene (VDRG) polymorphism can be used as a predictor for bone turnover rate or bone mass remains controversial. Its role within various ethnic populations are also unsettled. We examined VDRG polymorphism using restrictive enzymes Bsm-I, Apa-I, and Taq-I in 155 men aged 22-88 and 113 premenopausal women aged 40-53. The bone mineral density (BMD) of the vertebrae (L2-4), proximal femur, and total body bone mineral content (tb-BMC) (women only), as well as urinary N-terminal crosslinked fragment of type I collagen (NTX), serum osteocalcin, bone isozyme of alkaline phosphatase, and caboxyterminal propeptide of type I procollagen levels were measured. Chinese men and women exhibited a low prevalence for B (absence of Bsm-I restriction site) phenotypes than white and Japanese. Within the tested samples there were 0.4% BB homozygotes, 6.7% Bb heterozygotes, and 93% bb homozygotes. The distributions of Apa-I polymorphism (9.0% AA, 42.5% Aa, and 48.5% aa) also differed from those reported for the white populations. Most of the Chinese men and women were TT homozygous (96.6%). A comparison of actual values and values adjusted for age and weight of tb-BMC and BMD at the lumbar spine, Trochanter, Ward's triangle, and femoral neck showed no significant difference among three subgroups in each of the three sets of polymorphism. Furthermore, the actual values and adjusted values (adjusted for age) of the four bone markers, respectively, showed no significant differences. We conclude that given the very low prevalence of the suspected high risk genotypes (B, A, and t), and the lack of difference among the polymorphic subgroups, VDRG polymorphism may not be an important determinant of the bone turnover rate and bone mass of Chinese men and women.     

HMPAO brain SPECT in acute carbon monoxide poisoning

Technetium-99m-hexamethylpropylene amine oxime (HMPAO) brain images with fanbeam SPECT, in combination with surface three-dimensional display, were used to detect basal ganglion and cerebral cortex anomalies in the acute phase of carbon monoxide (CO) poisoning. METHODS: Ten patients, aged 16-29 yr, with acute CO poisoning and no past history of neurologic disorders were enrolled in this study. After oxygen treatment, all 10 patients were investigated using 99mTc-HMPAO brain images with fanbeam SPECT and surface three-dimensional display. Meanwhile, 6 of 10 patients also received a brain CT scan. RESULTS: CT scan findings were negative in all 6 patients. Fanbeam SPECT demonstrated unilateral or bilateral hypoactivity of basal ganglia in 6 patients. Local hypoactivity anomalies were found in the brain cortex of 7 patients, using surface three-dimensional display of the brain. Only 2 of 10 patients had normal 99mTc-HMPAO brain images. CONCLUSION: This study suggests that, in comparison with traditional brain imaging techniques, 99mTc-HMPAO brain imaging with fanbeam SPECT in combination with surface three-dimensional display is a better tool for early detection of regional cerebral anomalies in acute CO poisoning.     

Tunable erbium-doped fiber laser with a reflection Mach-Zehnderinterferometer

The concept of a tunable erbium-doped fiber ring laser based on a reflection Mach-Zehnder interferometer is presented. The principle of operation is demonstrated with a fiber version of the interferometer which gave a tuning range of 39 nm. With current electro-optic devices, high speed tuning should be possible     

Removal of boron from ceramic industry wastewater by adsorption-flocculation mechanism using palm oil mill boiler (POMB) bottom ash and polymer

Boron is extensively used in the ceramic industry for enhancing mechanical strength of the tiles. The discharge of boron containing wastewater to the environment causes severe pollution problems. Boron is also dangerous for human consumption and causes organisms' reproductive impediments if the safe intake level is exceeded. Current methods to remove boron include ion-exchange, membrane filtration, precipitation-coagulation, biological and chemical treatment. These methods are costly to remove boron from the wastewater and hence infeasible for industrial wastewater treatment. In the present research, adsorption-flocculation mechanism is proposed for boron removal from ceramic wastewater by using Palm Oil Mill Boiler (POMB) bottom ash and long chain polymer or flocculant. Ceramic wastewater is turbid and milky in color which contains 15 mg/L of boron and 2000 mg/L of suspended solids. The optimum operating conditions for boron adsorption on POMB bottom ash and flocculation using polymer were investigated in the present research. Adsorption isotherm of boron on bottom ash was also investigated to evaluate the adsorption capacity. Adsorption isotherm modeling was conducted based on Langmuir and Freundlich isotherms. The results show that coarse POMB bottom ash with particle size larger than 2 mm is a suitable adsorbent where boron is removed up to 80% under the optimum conditions (pH = 8.0, dosage = 40 g bottom ash/300 ml wastewater, residence time = 1 h). The results also show that KP 1200 B cationic polymer is effective in flocculating the suspended solids while AP 120 C anionic polymer is effective in flocculating the bottom ash. The combined cationic and anionic polymers are able to clarify the ceramic wastewater under the optimum conditions (dosage of KP 1200 B cationic polymer = 100 mg/L, dosage of AP 120 C anionic polymer = 50 mg/L, mixing speed = 200 rpm). Under the optimum operating conditions, the boron and suspended solids concentration of the treated wastewater were reduced to 3 mg/L and 5 mg/L respectively, satisfying the discharge requirement by Malaysia Department of Environment (DOE). The modeling study shows that the adsorption isotherm of boron onto POMB bottom ash conformed to the Freundlich Isotherm. The proposed method is suitable for boron removal in ceramic wastewater especially in regions where POMB bottom ash is abundant.     

Simulations and experiments for optimal deployment of an RFID‐based location‐aware system

The proliferation of communication and mobile computing devices and local‐area wireless networks has cultivated a growing interest in location‐aware systems and services. An essential problem in location‐aware computing is the determination of physical locations. RFID technologies are gaining much attention, as they are attractive solutions to indoor localization in many healthcare applications. In this paper, we propose a new indoor localization methodology that aims to deploying RFID technologies in achieving accurate location‐aware undertakings with real‐time computation. The proposed algorithm introduces means to improve the accuracy of the received RF signals. Optimal settings for the parameters in terms of reader and reference tag properties were investigated through simulations and experiments. The experimental results indicate that our indoor localization methodology is promising in applications that require fast installation, low cost and high accuracy. Copyright © 2009 John Wiley & Sons, Ltd.