Evaluation of general aviation management at Denver Stapleton airport

The potential benefits of general aviation management at a major airport is examined in this paper. The three general aviation management techniques investigated are volume reduction, runway segregation and time restriction.

First, a methodology for analyzing these techniques is discussed. The various effects on each user group are quantified for economic comparison between each management technique attempted. A computer simulation model was used to measure the delay effects. Then, these techniques are applied to Denver Stapleton Airport to measure their effects in present and future scenarios.

The results show that the best general aviation management technique is volume restriction. The use of peak‐hour pricing mechanism provided better results than random rejection, particularly if only a small degree of diversion is desired. The construction of a new general aviation runway provided equivalent results to the best technique tested.     

Goods transport in Etarea

Etarea is a planned satellite town for Prague, the capital of Czechoslovakia, located some 10 km from the outskirts of the capital. Its projected population of 135,000 will live in 13 residential areas, each of which will have its own retail centre in addition to the main retail centre.The plans for Etarea incorporate a unique approach to the related problems of the storage and distribution of goods within urban areas. All incoming goods will be delivered by road or rail, and possibly in the future by water, to a central storage complex. Goods for the retail trade are distributed from this central store by automated trains pulled by battery-powered trucks, each train having a capacity of 8.75 tons. The trains, which run in a network of underground tunnels, 2 \sX 2.5 meters in cross section, are guided by an optical sensing system. The underground network comprises 3 main routes with branches serving the individual centres. Secondary storage facilities are planned for each of the 14 retail centres where unit loads received from the main storage centre are subdivided for retail sale.One of the proposed methods of retail distribution provides for the fully automated delivery of goods from the retail centres direct to the consumer's household. This is accomplished by means of a pneumatic tube system similar to that used for handling cash in some large stores. Orders will be placed by dialling the code number assigned to the required item, given in a catalogue of available goods. Provided that the customer's account is in credit the order will be accepted and the goods automatically dispatched from the local centre; delivery is estimated to take between 2.5 and 11.5 minutes depending on the distance of the customer's house from the centre. The same system is utilised for the delivery of regular orders for such items as newspapers and magazines as well as for mail and for the the removal of household refuse. In addition to the automated system each retail centre will also have over-the-counter, self-service and slot machine facilities for the sale of goods.All proposals for goods storage and distribution planned for Etarea are based on existing technologies.     

Distributed support modelling for vertical track dynamic analysis

The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the ‘pinned–pinned’ vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.     

Reliability Modeling and Maintenance Policy Optimization for Deteriorating System Under Random Shock

Performance degradation and random shock are commonly regarded as two dependent competing risks for system failures. One method based on effective service age is proposed to jointly model the cumulative effect of random shock and system degradation, and the reliability model of degradation system under Nonhomogeneous Poisson processes (NHPP) shocks is derived. Under the assumption that preventive maintenance (PM) is imperfective and the corrective maintenance (CM) is minimal repair, one maintenance policy which combines PM and CM is presented. Moreover, the two decision variables, PM interval and the number of PMs before replacement, are determined by a multi-objective maintenance optimization method which simultaneously maximizes the system availability and minimizes the system long-run expect cost rate. Finally, the performance of the proposed maintenance optimization policy is demonstrated via a numerical example.     

肿瘤免疫研究的回顾与展望

20多年来,本校免疫病理研究室一直从事肿瘤免疫的研究,从研究肿瘤浸润淋巴细胞的活化和肿瘤逃逸的机制开始,到探索诱导浸润淋巴细胞(tumor infiltrating lymphocytes, TIL)活化的最佳条件,并将这些研究结果转化为肿瘤免疫治疗和免疫预防的实践,从一个侧面反映了人类在征服肿瘤道路上的艰苦历程。     

IAA与HRP联合作用对人胰腺癌BXPC-3的细胞毒效应

目的　研究吲哚乙酸(IAA)与辣根过氧化物酶(HRP)在体外共同作用于人胰腺癌BXPC 3 细胞所产生的细胞毒效应。方法　MTT法测定IAA/HRP对BXPC 3细胞增殖的影响;流式细胞仪分析BXPC 3 细胞周期时相变化;胎盘兰(曲利本兰)排斥试验,研究IAA/HRP对BXPC 3 细胞死亡率的影响;原位细胞凋亡检测试剂盒检测IAA/HRP作用后BXPC 3细胞的凋亡。结果　IAA/HRP体外对BXPC 3 细胞有抑制生长的效应,且这种效应有浓度和时间依赖性;BXPC 3细胞在IAA/HRP作用48 h后细胞周期被阻滞在G1期和G2期;IAA/HRP作用72 h后对照组和药物组的凋亡细胞数存在着显著性差异,且凋亡细胞数有浓度依赖性。结论　IAA/HRP对胰腺癌BXPC 3 细胞有细胞毒作用,可体外抑制细胞的增殖,诱导凋亡。     

萘乙酸抑制K562细胞增殖作用的初步研究

目的研究萘乙酸(NAA)对K562细胞增殖的抑制作用。方法应用MTT法、细胞计数法、流式细胞术、分裂指数分析、tunnel法以及姊妹染色单体交换(sister chromatid exchange,SCE)和微核制备,对NAA处理的K562细胞进行细胞增殖、细胞周期、凋亡以及染色体损伤检测。结果与对照组相比,NAA可以有效抑制K562细胞的生长,并将细胞阻滞在G1期,降低细胞分裂指数,促进细胞凋亡,提高K562细胞SCE频率以及微核形成率。结论NAA具有抑制K562细胞增殖的作用。