公路标线道钉的疲劳试验研究

从设计及数据处理方面介绍了公路标线道钉的疲劳试验,同时对试验的设计思想与试验方法作了详尽的阐述,得出了理想的结论。

玻璃中的玻璃态夹杂物——线道和节瘤

线道和节瘤是玻璃中的玻璃态夹杂物。详细分析了它们产生的各种原因,为生产中解决条纹节瘤缺陷提供了依据。

数字强震仪线道和极性的现场安装判断与纠正

强震记录对于地震科学研究、抗震设计理论、政府救灾决策非常重要。由于数字强震仪的线道和极性与出厂标称值不一致的情况不在少数,本文提出了一个集测定、纠正、存档为一体的现场安装工作方法。它简单、准确,其工作增量也减少到相当于1次2分钟的脉动测试。

双线道杂果智能分级机分级系统分析研究

针对杂果分级的必要性和重要性,以及如何通过双线道分级系统提高生产效率,降低串果率等问题,文中对其关键部分的智能分级系统进行分析、阐述和说明。并通过具体试验数据分析表明,大型杂果如油桃、杏、砂糖橘的分级能力可达3t/h以上,小型杂果如圣女果、冬枣等的分级能力可达1.2t/h以上,分级效率成倍提高。分级精度更加精准可靠,分级级数设定为5级,串果率为5%以下。

浮法玻璃边部线道成因分析及对策

浮法玻璃成形过程中形成的边部线道影响产品质量,扩大原板宽度并切除又影响了总成品率。边部线道产生的原因是由于流道闸板后的玻璃液轮廓线和流道池壁的玻璃液流出唇砖后部分折叠、回流到湿背砖所形成的变形线所致,可以通过增加定边砖的方式减少边部线道的影响,并从设计、施工的角度提出改进方案与建议。

浅谈国省线道公路工程档案管理问题及策略分析

本文通过查阅大量的资料,对现阶段公路工程档案管理工作的缺乏相应的公路档案管理意识、公路档案管理工作的规范性不足、档案管理人员素质不足等管理上的问题进行了总结,提出了优化公路工程档案管理工作的增加在公路工程档案管理中的投入、提高公路档案管理工作的规范程度、提升档案管理人员的专业能力等管理策略,以提高国省线道公路工程档案管理的质量。

500t A线“线道、节瘤”缺陷的治理方法

该文根据熔窑、锡槽操作的相关背景资料,再结合浮法熔窑的物理计算机模型的模拟结果,来寻找熔窑方面产生缺陷的根源。优化熔窑操作能减少“线道、节瘤”缺陷的产生,合理使用搅拌器是根治“线道”缺陷的一种手段。

Selective depression effect in flotation separation of copper-molybdenum sulfides using 2,3-disulfanylbutanedioic acid

2,3-disulfanylbutanedioic acid（DMSA） was found to be a selective depressant in the flotation separation of coppermolybdenum sulfides.The flotation results suggest that a low dosage of DMSA has a strong depression effect on chalcopyrite in the p H range between 4 and 12.At p H 6,the recoveries of molybdenum are up to 85%,75%,and 80% while those of chalcopyrite are 15%,5%,and 20% respectively when flotation tests are carried out with single minerals,mixed minerals and molybdenum-bearing copper concentrates.Adsorption isotherms measurement indicates that DMSA adsorbs more strongly on chalcopyrite than on molybdenite.The frontier orbital calculation reveals that the two S atoms of DMSA molecule are active centers for the adsorption of the DMSA molecule on chalcopyrite surface.Fermi level calculation shows that chalcopyrite can obtain electrons from the DMSA molecule while molybdenite cannot.

Influence of dye molecular structure on electron transfer in 2,9,16,23-tetracarboxy zinc phthalocyanine sensitized solar cell

2, 9, 16, 23-tetracarboxy zinc phthalocyanine （ZnTCPc） is synthesized and characterized by physicochemical and theoretical methods and it is used as a photosensitizer in dye-sensitized solar cells （DSSC）. The excited lifetime, band gap and frontier orbital distribution of ZnTCPc are investigated by fluorescence spectra, cyclic voltammetry and quantum calculation. The results show that the excited lifetime and band gap are 0. 1 ns and 1.81 eV, respectively. Moreover, it is found that the highest occupied molecular orbital （HOMO） location is not shared by both the zinc metal and the isoindoline ligands, and the lowest unoccupied molecular orbital（LUMO） location does not strengthen the interaction coupling between ZnTCPc and TiO：. As a result, the ZnTCPc-DSSC gains a short-circuit current density of 0. 147 mA/cm2, an open-circuit photovoltage of 277 mV, a fill factor of 0. 51 and an overall conversion efficiency of 0. 021%.

Pinacidil reduces neuronal apoptosis following cerebral ischemia-reperfusion in rats through both mitochondrial and death-receptor signal pathways

Objective To investigate effect of pinacidil, an ATP sensitive potassium channel （KATP） opener, on the neuronal apoptosis and its signaling transduction mechanism following focal cerebral ischemia-reperfusion in rats. Methods One hundred male Wistar rats were randomly divided into four groups： A, sham-operated group; B, ischemia-reperfusion group; C, KATe opener treatment group; and D, KATe opener and blocker treatment group. The middle cerebral artery occlusion （MCAO） model was established by using the intraluminal suture occlusion method, neuronal apoptosis was determined by TUNEL staining, and expressions of caspase-8, caspase-9 and caspase-3 mRNA were detected by in situ hybridization. Results （1） The numbers of apoptotic neurons at 12 h, 24 h, 48 h, and 72 h were significantly less in group C than in groups B and D （P 〈 0.01 or P 〈 0.05）; and there was no difference between groups B and D at all time points （P 〉 0.05）. （2） The expressions of caspase-3 mRNA and caspase-8 mRNA at all times and the expressions of caspase-9 mRNA at 12 h, 24 h, 48 h, 72 h were significantly lower in group C than in groups B and D （P 〈 0.01 or P 〈 0.05）; and there were no differences between groups B and D at all time points （P 〉 0.05）. Conclusions KATP opener can significantly decrease the neuronal apoptosis and the expressions of caspase-3, caspase-8 and caspase-9 mRNAs following cerebral ischemiareperfusion. The neuronal apoptosis may be decreased by the inhibition of both mitochondrial and death-receptor signal pathways.

Research on detection of lane based on machine vision

To prevent a vehicle from departing the lane in assistant or automatic steering, real-time vision-based detection of lane is studied. The system architecture, detecting principle and lane model are described. Then the detecting algorithm of the lane image is discussed in detail. In this algorithm, several proper sub-windows in one image are first selected as the processing regions. To every sub-window, by means of such steps as appropriate pre-processing, edge detection and Hough transform, etc., the lane description features are extracted. Experimental results reveal that this detection method is of good real-time, high recognition reliability and strong robustness, etc., which can provide the decision-making foundation for the following automatic or assistant steering to some extent.

影响帮面缝合强度的因素有哪些?

鞋帮在缝制完成后,要经受绷帮、缝底、脱楦等工艺操作,受到不同程度的拉伸弯曲的作用。如果帮面缝合不牢固,就会出现开线等问题。同时成鞋在穿用过程中,也会受到摩擦、弯曲、撞击等强烈作用。

Traffic-aware static channel assignment algorithm in wireless mesh networks

A channel assignment algorithm with awareness of link traffic is proposed in multi-radio multi-channel wireless mesh networks. First, the physical interference model based on the signal-to-interference-plus-noise ratio and successful transmission condition is described. The model is more suitable for a wireless communication environment than other existing models. Secondly, a pure integer quadratic programming （PIQP） model is used to solve the channel assignment problem and improve the capacity of wireless mesh networks. Consequently, a traffic- aware static channel assignment algorithm（TASC） is designed. The algorithm adopts some network parameters, including the network connectivity, the limitation of the number of radios and the successful transmission conditions in wireless communications. The TASC algorithm can diminish network interference and increase the efficiency of channel assignment while keeping the connectivity of the network. Finally, the feasibility and effectivity of the channel assignment solution are illustrated by the simulation results. Compared witb similar algorithms, the proposed algorithm can increase the capacity of WMNs.

An enhanced iterative joint channel estimation and symbol detection algorithm for OFDM systems

For orthogonal frequency division multiplexing (OFDM) wireless communication, the system throughput and data rate are usually limited by pilots, especially in a high mobility environment. In this paper, an enhanced iterative joint channel estimation and symbol detection algorithm is proposed to enhance the system throughput and data rate. With lower pilot power, the proposed scheme increases system throughput firstly, and then the channel estimation and symbol detection proceed iteratively within one OFDM symbol to improve the BER performance. In the proposed algorithm, the original channel estimate of each OFDM symbol is based on the channel estimate of the previous OFDM symbol, thus the variation of the mobile channel is traced efficiently, so the number of pilots in the time domain can be reduced greatly. Besides reducing the system overhead, the proposed algorithm is also shown by simulation to give much better BER performance than the conventional iterative algorithm does.

Frequency responses of immersing tunnel element under wave actions

The immersion of large-scale tunnel elements is one of the most important working procedures in the construction of an underwater immersed tunnel. To investigate the dynamic characteristics of tunnel element in the process of immersion, based on the twin-barge immersing operation method, the frequency-domain analysis of the tunnel element motions under wave actions was made. The linear wave diffraction theory and the three-dimensional source distribution method were applied to calculate the wave loads and motion responses of the tunnel element under different incident wave conditions. In the study, movement of the two barges in the water was assumed to be small and was ignored. Cable tension was computed by the static method. On the basis of the above theories, a computer program was made, and two cases were taken to check the validity of the program. The results showed that wave loads acting on the immersed tunnel element are relatively large near the water surface, and they decrease with the increase of immersing depth of the tunnel element. Wave loads first increase, then decrease, with the increase of wave period. The motion responses of the tunnel element are also generally large near the water surface and decrease as the immersing depth increases.

A maximum-independent-set-based channel allocation algorithm for multi-channel wireless networks

A channel allocation algorithm based on the maximum independent set is proposed to decrease network conflict and improve network performance. First, a channel allocation model is formulated and a series of the maximum independent sets （MISs） are obtained from a contention graph by the proposed approximation algorithm with low complexity. Then, a weighted contention graph is obtained using the number of contention vertices between two MISs as a weighted value. Links are allocated to channels by the weighted contention graph to minimize conflicts between independent sets. Finally, after channel allocation, each node allocates network interface cards （NICs） to links that are allocated channels according to the queue lengths of NICs. Simulations are conducted to evaluate the proposed algorithm. The results show that the proposed algorithm significantly improves the network throughput and decreases the end to end delay.

Employing temporal channel correlation in user selection for MIMO broadcast systems

Taking the time varying nature of wireless channels into account, two user selection schemes with lower complexity are developed for multiple-input multiple-output broadcast （MIMO BC）systems. According to the relationship between coherence time and Doppler frequency, an information frame is divided into several segments. At the beginning of each segment, the user selection is carded out with the greedy selection algorithm. In the simplified user selection algorithms employing the temporal correlation （SUSTC）, the selection results are applied for all the remaining slots in each segment. But in the improved simplified user selection algorithms employing the temporal correlation（ISUSTC）, at the remaining slots, users are kept with favorable channel conditions selected at the previous slot, and other users are updated from the candidate pool to communicate simultaneously. Simulations show that compared with the greedy user selection method, the proposed algorithms can reduce the selection complexity with a little sum capacity loss.

超白玻璃熔窑卡脖处异形水包的开发使用

因为超白玻璃液黏度比普通浮法玻璃液小且黏度随温度波动不大,故随着超白玻璃熔窑长时间的运行,在窑炉中高温环境和超白玻璃液流动的侵蚀下,窑炉中的卡脖水包与池壁之间会出现间隙扩大、池壁变薄的问题,且因为卡脖池壁与水包之间间隙的扩大,卡脖水包侧面的玻璃液流动时会带动水包上凝固的玻璃液(不动层)形成化学线道。通过在卡脖水包前两侧插入小型异形水包,使卡脖水包处池壁砖受侵蚀部位前形成一层凉玻璃的不动层,从而减少池壁砖的被侵蚀程度,并且可以减少边部不动层被玻璃液带走形成化学线道的现象。

QoS-based MAC protocol for cognitive radio networks

In order to improve the throughput performance of the secondary users （SUs） in the cognitive radio （CR） environment, a quality of service （QoS） based media access control （MAC） protocol is proposed. In this protocol, the CR node maps the channel state as a vector, and the transmitter and the receiver obtain the final channel map through an AND operation to prepare for an optional channel set. Data from the upper application layer are classified into two priority levels according to the QoS requirement. The data of each level relate to different contention windows so that the priority of real time data can be guaranteed. A two-dimensional discrete-time Markov chain is utilized to evaluate the system performance, and mathematical expressions of the system throughput are derived. Simulation results show that compared with the IEEE 802. 11 distributed coordination function （DCF）, the proposed MAC protocol can achieve higher throughput.

Radio Channel Measurements and Analysis at 2.4/5GHz in Subway Tunnels

There is an increasing demand on wireless communications in subway tunnels to provide video surveillance and sensory data for security,maintenance and train control,and to offer various communication or entertainment services(e.g.,Internet,etc.) to passengers as well.The wireless channel in tunnels is quite unique due to the confined space and the waveguide effects.Therefore,modeling the radio channel characteristics in tunnels is critically important for communication systems design or optimization.This paper investigates the key radio channel characteristics of a subway tunnel at 2.4 GHz and 5 GHz,such as the path loss,root mean square(RMS) delay spread,channel stationarity,Doppler shift,and channel capacity.The field measurements show that channel characteristics in tunnels are highly location-dependent and there exist abundant components in Doppler shift domain.In the straight section of the subway tunnel,the measured path loss exponents are close to1.6,lower than that in free space.