ECONOMIC DESIGN OF REFRIGERATED AUTOMATED STORAGE AND RETRIEVAL SYSTEMS

The objective of this paper is the development of a design model for refrigerated automated storage and retrieval systems (R-AS/RS). Compared with ordinary unit-load AS/RS, the R-AS/RS under this study has several different design and operating characteristics: (I) greater emphasis is placed on the storage function and so it has a double-depth lane in the storage rack; (2) cooling units are required to maintain a cold temperature environment in the system; (3) the maximum number of storage orders handled per unit time is limited by the system capacity. Considering the above characteristics, the design problem is formulated as a non-linear mixed integer programming problem in which the cost of the system is minimized. The decision variables are the storage volume, the number of storage and retrieval (S/R) machines, the type and number of cooling units, and the physical configuration of the building. A case problem is solved to illustrate the model.     

Sodium Diffusion in Glass: I, Single-Alkali Silicate

The isotope effect for ²²Na/²⁴Na diffusion was measured for three 25-mol% alkali-silicate glasses. A multiple diffusion mechanism wherein the Na ions diffuse both singly (vacancy mechanism) and in pairs (interstitialcy mechanism) provided the best agreement with the experimental data. According to this tentative model, diffusion by Na ion pairs predominates at low temperatures, and the fraction of Na ions diffusing singly increases with increasing temperature. In the glasses investigated, nearly all of the Na ions diffuse singly in the vicinity of the transformation range.     

Growth of nitrogen-doped p-type ZnO thin films prepared by atomic layer epitaxy

Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2[Diethylzinc,DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·m with a hole concentration of 3.71×1017cm-3 . Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is ap-type semiconductor.     

Robust and fault-tolerant supervisory control of discrete event systems with partial observation and model uncertainty

This paper proposes the notions of faults and failures in discrete event systems (DESs) with partial observation. They are associated with controllability and an observability property. The proposed notions are used to address the notion of tolerable fault event sequences which represents fault-tolerant behaviour of systems as a desired specification. A robust and fault-tolerant supervisor is a controller which is robust to model uncertainty and guarantees fault-tolerant behaviour of a system. In this paper we present necessary and sufficient conditions for the existence of a robust and fault-tolerant supervisor. The developed conditions capture the concepts of controllability and observability which are cores in the control of DESs with partial observation     

改性六方氮化硼/水性聚氨酯防腐涂料制备与性能

以聚甘油-10(PG)作为稳定剂，在超声条件下对六方氮化硼(h-BN)进行剥离和改性。通过红外光谱(FT-IR)、热重分析(TG)、原子力显微镜(AFM)和透射电镜(TEM)对PG改性的h-BN纳米片(GB)进行了表征。将制备的PG纳米粒子用作水性聚氨酯(WPU)涂层的防腐填料，制备了GB质量分数分别0，0.5%，1.0%，2.0%的为复合涂层(PU/GB)。考察了不同涂层的水接触角、吸水率、附着力损失、热稳定性和机械性能。最后，通过电化学工作站研究了WPU、PU/GB0.5、 PU/GB1.0 和PU/GB2.0复合涂层在3.5%NaCl水溶液中的腐蚀行为。结果表明，GB纳米粒子可以显著增强水性聚氨酯涂层的耐水性、热稳定性、机械性能和耐腐蚀性能。     

羟基磷灰石／细菌纤维素纳米复合材料的制备与热力学性能表征

摘要通过仿生途径制备了模拟天然骨成分的羟基磷灰石／细菌纤维素（hydroxyapatite/bacterial cellulose,HAp/BC）纳米复合材料,使用TGA（thermo-gravimetric analysis）, DSC（differential scanning calorimetry）和DMA（dynamic mechanical analysis）测试方法对复合材料进行了热力学表征,以此来了解复合材料的成分组成、热稳定性和热力学行为．实验结果表明,纳米复合材料的成分与天然骨相似,并且热稳定性与纯BC相比有所提高;纳米复合材料在热分解时存在复杂的吸热放热现象;由于HAp的加入,与BC相比,复合材料的玻璃化转变温度向高温区域移动．     

Characterization of flexible copper laminates fabricated by Cu electro-plating process

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology, texture, hardness, electrical resistivity and folding behavior was evaluated. To achieve Cu layers with similar thicknesses, the current density was varied in the range of 0.2–3 A/dm² and the plating time was controlled in the range of 0.5–7.5 h to compensate for the variation of the current density. The surface morphology, hardness, and folding behavior were characterized by atomic force microscopy, nanoindentation technique and Massachusett Institute of Technology folding endurance test, respectively. The X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases; however, the preferred orientation changed from (220) to (111) as the current density increased over 1 A/dm². In addition, it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased simultaneously. The electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000, which were comparable to those of commercial FCCLs.     

DRIFT CONTROL OF HIGH-RISE BUILDINGS WITH UNIT LOAD METHOD

The use of displacement participation factors obtained by the unit load method provides an effective drift control tool for high-rise buildings. Structural sensitivity coefficients and displacement participation factors for members in a structure with respect to the lateral displacement to be controlled are computed and used for identifying active members and their corresponding displacement components. The drift control method using the displacement participation factors with a variable linking strategy is formulated into an optimization problem to determine the amount of material to be modified. Using the drift control method, a structural design model for a high-rise building is proposed and applied to one verifying example and two moment resisting frames. Time consuming trial-and-error processes related to the structural design of a high-rise building is avoided by the proposed structural design model. As demonstrated in the examples, the maximum lateral displacements of the examples are reduced by 57·05, 40·0 and 16·36% without changing the total weights of the structures. © 1997 John Wiley & Sons, Ltd.     

Sediment provenance discrimination in northern Okinawa Trough during the last 24 ka and paleoenvironmental implication:rare earth elements evidence

Rare earth elements(REE) compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka,especially for the influence from the Yellow River and the Tsushima Warm Current(TWC) that has not been well solved.Variations of these parameters were clearly divided into three distinct depositional units.During Interval 1(24.1-16.0 ka BP),the paleo-Yellow River and the paleo-Yangtze River mouths were situated near the studied area and could have played major roles in the sedimentation therein.In Interval 2(16.0-7.3 ka BP),these river mouths gradually retreated with global sea-level rise,leading to less fluvial inputs from them to the northern Okinawa Trough.Meanwhile,formation of the TWC could carry some sediment loads of Taiwan to the studied core,especially during its late phase(8.0-7.3 ka BP).Modern oceanographic conditions,with a predominance of the TWC,were finally established since the beginning of Interval 3,causing more terrigenous contribution from Taiwan to the studied area.Sub-sequently,modern depositional environments mainly influenced by the Yellow River,the Yangtze River,and the TWC were finally formed.