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51.
Given a quality-of-service constraint, a wireless network has to sacrifice its capacity in order to support an increase in mobility. In other words, the network needs to convert some of its capacity into mobility. We develop an analytical model to evaluate the efficiency of the mobility/capacity conversion processes of several wireless networks. One practical implication of our results is that a network, if designed correctly, should have a free convertibility between the two. 相似文献
52.
Catanzaro I Avellone G Marcì G Saverini M Scalici L Sciandrello G Palmisano L 《Journal of hazardous materials》2011,185(2-3):591-597
The aim of this work was to study the biological effects of four monoterpenes, i.e. α-pinene, β-pinene, 3-carene and D-limonene present in the wastewater of a citrus transformation factory. The study was carried out by exposing V79 Chinese hamster cells to single terpene or to the mixture of four terpenes at concentrations corresponding to those in the wastewater evaluated by head space solid phase micro extraction and gas chromatography (HS-SPME-GC) analyses. Treatments with single or combined terpenes similarly affected cell vitality, but only the combined treatments induced the 6-thioguanine resistant mutants. Moreover the photocatalytic degradation of the four terpenes was successfully achieved with the photocatalyst TiO(2) Degussa P25 in both the actual effluent and in synthetic solutions. 相似文献
53.
Previous research examined sanitation treatments on cut cantaloupe tissue to deliver germicidal and food safety effects. However, an apparent compromise between volatile loss and treatment/sampling efficacy appeared. Subsequently, a physiological and volatile reassessment of thinly sliced tissue against cubes was performed in cantaloupe tissue. Thin sliced cantaloupe L* decreased 27.5%, 40.5%, and 52.9% in 3, 2, and 1 mm thickness, respectively, compared with cut cubes after 3 d. Overall color (C) decreased in freshly prepared cubes (2.4%) and slices (14.4%) that were washed in cold water. Surface area per unit volume (SA: vol) in slices was 4.1 times greater than typical cubes, as reflected by substantial water loss (20.4%, 9.5%, and 6.7% in 1, 2 and 3-mm slices, respectively) after 1 d at 5 °C. Rinsing cubes and thin-slices with 5 °C deionized water resulted in roughly 15% soluble solids loss. SEM indicated 65.4% reduced cell size in 1-d old thin slices, evidenced by excessive cell damage and desiccation compared with stored fresh-cut cubes. In thin-sliced tissue exposed 15 min to an open atmosphere (mimic sanitation treatments), total esters decreased 92.8% and 95.8%, respectively, after 1 and 3 d storage at 5 °C. Washing tissue provided a boundary layer that reduced short-term ester losses in slices and cubes. Excessive cutting, sanitation treatment regimes, and storage can radically alter the desirable volatile profile of cut cantaloupe. Reduction of tissue size to maximize food-safety sanitation efficacy or delivering items to a niche market will need substantial work to engineer equipment and develop protocols to insure that product quality and volatiles are not compromised. PRACTICAL APPLICATION: We have demonstrated that cutting method and sampling protocol are critically important when using volatiles as a means by which to assess or interpret stress response and ascribe fresh-cut quality. Reduction of tissue size to maximize food-safety sanitation efficacy (for example, thin slices) will need substantial work to engineer equipment and design protocols to insure product quality and volatile profiles are not compromised. 相似文献
54.
An Chen Wong A.K.-S. Lea C.-T. 《Selected Areas in Communications, IEEE Journal on》2004,22(9):1648-1657
Optical time-division multiplexing (O-TDM) networks can provide a finer bandwidth granularity than wavelength-division multiplexing networks, and will play an important role in future all-optical networks. Since optical buffers are expensive, a small buffer size will be the characteristic of O-TDM systems. This paper analyzes the problem of routing and time-slot assignment in O-TDM networks. The results lead to the proposal of a Dijkstra-like shortest-path routing scheme that intends to maximize the performance of an optical network with a small number of optical buffers. Performance evaluation of the proposed scheme is also presented. 相似文献
55.
The existence and ionic conductivity of solid solutions Na1+xM
x
III
Zr2–x(PO4)3 with Nasicon-like structure have been investigated and the results compared with literature data. A limited range of solid solutions is formed with MIII = aluminium, gallium, yttrium, ytterbium, whereas a continuous series is obtained for MIII = chromium, iron, scandium, indium. The pure end member Na3ln2(PO4)3 is reported for the first time; according to powder diffraction data, it is hexagonal witha = 0.8966(1) andc = 2.2104(4) nm. The small monoclinic distortion already known for MIII = chromium, iron and scandium is restricted tox values very close to 2. Ionic conductivity measurements show that for a given value ofx, the mobility of the Na+ ions is strongly influenced both by the ionic radius and the type of electronic structure of the MIII ion. However, no simple correlation can be found. 相似文献
56.
Lea Heikinheimo Arja Miettinen‐Oinonen Artur Cavaco‐Paulo Johanna Buchert 《应用聚合物科学杂志》2003,90(7):1917-1922
The mode of action of monocomponent purified Trichoderma reesei cellobiohydrolases (CBHI and CBHII) and endoglucanases (EGI and EGII) on cotton fabrics was studied by analyzing the weight loss of the fabric, the reducing sugars, the soluble oligosaccharides and the molecular weight of the cotton powder formed. The impact of mechanical action on these factors was also evaluated. EGI and EGII released the highest amounts of reducing sugars and soluble oligosaccharides in both treatments with or without additional mechanical action. After cellulase treatment without additional mechanical action, all of the cellulases were found to have reduced the molecular weight of cotton poplin powder. When mechanical action was combined with enzyme treatments, only EGII reduced the molecular weight. The weight loss of EG‐treated fabrics was clearly higher than the weight loss of CBH‐treated fabrics with both low and high mechanical action levels. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1917–1922, 2003 相似文献
57.
A cesium fountain frequency standard: preliminary results 总被引:9,自引:0,他引:9
Clairon A. Laurent P. Santarelli G. Ghezali S. Lea S.N. Bahoura M. 《IEEE transactions on instrumentation and measurement》1995,44(2):128-131
An atomic frequency standard based on a fountain of cold cesium atoms has been in operation in our laboratory for a few months. Ramsey fringes as narrow as 0.7 Hz have been obtained. The short-term frequency stability, measured against an H-maser, is 3 10-13 τ-1/2, probably limited by the local oscillator frequency noise. A preliminary evaluation of some systematic effects shows that cold collisions will be the limiting effect for long-term stability and accuracy. Measurements of this shift presented here, using a magnetooptical trap, show that at low density an uncertainty of about 10 15 is obtained. Under these conditions, the number of atoms is large enough to allow a potential stability of 10-13 τ -1/2 to be reached. When optical molasses is used, the initial density is lower and collisional effects are reduced by a factor of three 相似文献
58.
59.
New developments in deoxyribonucleic acid (DNA) technology are increasing understanding of the role of genetics in health and disease. This kind of health information requires that perioperative nurses develop new skills and roles that will enhance the quality of genetic health care they provide to patients, particularly with regard to managing genetic information. Perioperative nurses expand their scope of practice to incorporate a genetic focus into health assessment, patient education, and patient support as they assimilate new genetic information into their daily lives. Perioperative nurses familiar with genetic counseling services--and how and when to refer patients for such services--will ensure that all patients have access to the most current and appropriate genetic information with which to make informed health choices. 相似文献
60.
人工举升装置的新进展 总被引:2,自引:0,他引:2
本文从三个方面介绍了人工举升装置的新进展。即:有杆泵采油装置,螺杆泵采油装置和气举采油装置。在人工举升装置中,有杆采油装置处于主导地位。本文介绍的九种有杆采油新技术包括:新型固定凡尔罩。三种经改进的盘根盒;泵入口气体分离器。计算机油井监控器,经改进的清蜡装置,聚乙烯油管衬管;处理气井产出水的新方法。三种螺杆泵新技术包括:新型金属定子;防止泵故障的流量控制器和防止倒扣的油管接箍锁定装置。两种气举采油新技术为:连续油管的钢丝绳可回收阀和在美国西得克萨斯油田应用的CO_2气举法。 相似文献