Dynamic change of aircraft seat condition for fast boarding

Aircraft boarding is a process mainly impacted by the boarding sequence, individual passenger behavior and the amount of hand luggage. Whereas these aspects are widely addressed in scientific research and considered in operational improvements, the influence of infrastructural changes is only focused upon in the context of future aircraft design. The paper provides a comprehensive analysis of the innovative approach of a Side-Slip Seat, which allows passengers to pass each other during boarding. The seat holds the potential to reduce the boarding time by approx. 20%, even considering operational constraints, such as passenger conformance to the proposed boarding strategy. A validated stochastic boarding model is extended to analyze the impact of the Side-Slip Seat. The implementation of such fundamental change inside the aircraft cabin demands for adapted boarding strategies, in order to cover all the benefits that accompany this new dynamic seating approach. To reasonably identify efficient strategies, an evolutionary algorithm is used to systematically optimize boarding sequences. As a result, the evolutionary algorithm depicts that operationally relevant boarding strategies implementing the Side-Slip Seat should differentiate between the left and the right side of the aisle, instead of the current operationally preferred boarding from the back to the front.     

大跨径预应力混凝土梁桥长期挠度控制分析

目前国内大跨径预应力混凝土梁桥存在的主要病害是跨中下挠过大和箱梁梁体裂缝。本文对跨中下挠过大的主要原因进行了分析,介绍了施工控制中线形控制的方法,然后用恒载零弯矩理论给一座已建的95 160 95m连续刚构桥重新配置预应力束,并对原设计和恒载零弯矩配束从内力、位移、预应力筋用量三方面作一比较, 最后提出了控制跨中下挠过大的一些措施。     

Cost effective future derailment mitigation techniques for rail freight traffic management in Europe

Safe and reliable traffic management is vital for uninterrupted and successful operation of the European rail network, where mixed traffic (i.e. freight and passenger) services are run. Although rail freight derailment is infrequent, its consequences can be severe and may result in different forms of costs, including infrastructure; rolling stock; traffic disruptions; injuries and fatalities. The objective of this research paper is to conduct a cost benefit analysis (CBA) to identify cost effective mitigation techniques for efficient rail freight traffic management in Europe, by 2050. Reviewing previous derailments and studies, eight sets of derailment causes are analysed and, for each of them, sets of mitigation techniques are aimed at for their alleviation. The study finds that the highest cumulative costs of derailment are associated with ‘wheel failure’, while the lowest cumulative cost is identified for ‘excessive track width’. Regarding mitigation techniques, the lowest cumulative benefits are demonstrated for ‘track height’ interventions, whereas ‘wheel failure’ alleviation demonstrates the highest benefits, in value terms (all by 2050). In most cases, the benefit to cost ratio did not exceed 2.6; in two cases (‘track height’ and ‘rail failures’) the ratio remained below 1 – a negative outcome where cost is higher than benefit. The study suggests that the most cost-efficient interventions are those applied to ‘hot axle box and axle rupture’ and ‘spring and suspension failure’.     

妊高征患者血浆内皮素水平和血液流变学指标的动态变化

测定了３０例妊娠３０～４２周孕妇（２０例妊高征，１０例正常孕妇）血浆内皮素（Ｅｎｄｏｔｈｅｌｉｎ，ＥＴ）水平和血沉（ＥＳＲ），红细胞压积（Ｈｔ），全血粘度（ＷＢＶ）及血浆粘度（ＰＶ），并动态观察了５例病程较长妊高征患者血浆ＥＴ水平。结果显示，妊高征母体血浆ＥＴ水平显著高于正常孕妇，且随着病程延长和病情加重而有升高；妊高征组Ｈｔ及ＷＢＶ明显高于正常孕妇组，而ＥＳＲ则明显缓慢。两组ＰＶ无明显变化。妊高征组血浆ＥＴ水平与Ｈｔ及ＷＢＶ呈显著正相关，与ＥＳＲ及ＰＶ呈显著负相关。提示血浆ＥＴ水平及其动态变化与妊高征的严重程度呈正相关，可作为其病情判别和母婴预后估计的辅助指标。     

Efficient estimation of extreme long-term stresses by considering a combination of longitudinal bending stresses

Longitudinal stresses due to combined horizontal and vertical bending moments in ships, corresponding to a return period of 20 years, are estimated by linear response analysis. In principle, the stress should be obtained by combining the stress in all sea states that can occur over a long-term period. A method to determine the desired long-term extreme stress by considering only a few short-term sea states is presented. The sea states have a certain probability of occurrence, and are each identified by a contour line in the (H _s, T _p)-plane. This approach makes it possible to estimate the extreme loads on the vessel in a practical and accurate manner. Moreover, it is shown that the long-term stress can be estimated by combining the individual long-term extreme stresses due to vertical and horizontal bending moments by using the sum-of-squares approach and accounting for the correlation between stresses. It was found that the correlation coefficient can be taken as the largest of the ones calculated along the contour line. It is shown that this correlation coefficient can even be approximated by the normalized phase angle at the wave length where the dominant response has its peak value. A comparison with the results obtained using well-known combination rules is presented. While linear analysis has been used here, it is believed that the approach can be generalized to stresses with nonlinear behavior, and hence represent a significant improvement in calculation efficiency. Received: September 18, 2001 / Accepted: December 18, 2001     

A summary of the formation and seasonal progression of the Northeast Water Polynya

A summary of the seasonal development of the Northeast Water Polynya ice cover characteristics is presented. This is based primarily on satellite remote sensing observations, with some in situ measurements, including both new and published data.     

准确确定海船初稳性高度界限面及综合稳性界限面的方法探讨

本文介绍了确定船舶初稳性高度界限面和综合稳性界限面的准确方法，通过对初稳性高度界限面问题的讨论，完善了载荷变动求取船舶初稳性高度变化量及改变载荷调整船舶初稳性高度的理论计算公式，并为船舶驾驶员在载荷变动时判断船舶初稳性高度的变化情况提供了准确可靠的方法。通过对船舶综合稳性界限面问题的讨论，建立了改变载荷求取船舶综合稳性变化量及调整船舶综合稳性的理论计算公式，为船舶驾驶员在载荷变动时判断船舶综合稳性的变化情况提供了准确可靠的方法。     

绞吸挖泥船作业产量的现场优化技术

根据绞吸挖泥船疏浚作业产量现场优化技术研制出的辅助决策系统可直接安装在挖泥船上,根据水下土质变化情况,通过建立改进疏浚工艺的数学模型,采用电子信息技术进行疏浚产量的现场寻优,实现高产稳产,平均提高工效30%以上。     

抵抗素、C反应蛋白与早期2型糖尿病微血管病变的关系

目的 探讨2型糖尿病(T2DM)患者血浆抵抗素、血清C反应蛋白(CRP)水平与早期T2DM微血管病变的相关性.方法 选取60例临床确诊的T2DM患者,按有无微血管并发症分为微血管并发症组(DMA组)和无微血管并发症组(NDC组),每组30例.另选取24例同期体检的健康志愿者作为对照组(NC组).采用双抗体夹心酶联免疫吸附试验测定3组的血浆抵抗素含量,散射免疫比浊法测定血清CRP含量,放射免疫分析法测定胰岛素,氧化酶法测定血糖,全自动生化分析仪检测血脂.结果 ①DMA组血浆抵抗素、血清CRP含量均高于NDC组及NC组,差异有统计学意义(P＜0.05).②Pearson(或Spearman)相关分析显示,血浆抵抗素与空腹胰岛素(FIns)、糖化血红蛋白(HbA1c)、胰岛素抵抗指数(HOMA-IR)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)呈正相关(r分别为0.582、0.433、0.435、0.342、0.485,P均＜O.05),与空腹血浆葡萄糖(FPG)、甘油三酯(TG)、体质指数(BMI)、高密度脂蛋白胆固醇(HDL-C)均无相关性;血清CRP与尿微量白蛋白(UALb)、血浆抵抗素、HOMA-IR、FIns、HbA1c呈正相关(r分别为0.388、0.240、0.283、0.279、0.318,P＜O.05),与HDL-C呈负相关(r=0.235,P＜O.05).结论 血浆抵抗素、血清CRP可能与2型糖尿病微血管病变的发生、发展有密切关系.