大型通道中主动式水雾抑爆现象的实验研究

采用自制的主动水雾抑爆器,对主动水雾抑爆过程中的激波、火焰抑制作用进行了实验研究。实验结果表明:采用主动水雾抑爆时,在水雾区及其后的一定距离内激波均表现出不同程度的衰减,激波衰减随水雾空间密度增加而明显;当水雾区长度为1.6m时,在48.75kg/m3附近存在一个水雾密度临界值,水雾密度低于此值时,激波穿过水雾区后会再次成长增强,不能发生完全抑爆;保持水雾空间密度32.5kg/m3不变时,水雾区越长,激波衰减作用越明显;在2.5～3.0m之间存在一个激波完全衰减成为压缩波的水雾区临界长度。可以预知,随水雾区密度和长度变化,存在一抑爆临界曲线,此曲线将整个试验范围划分为抑爆区和非抑爆区两部分。

大型通道中粉尘爆炸的数值模拟

将火焰阵面视作无限薄的内边界,流场被分为两部分。根据火焰阵面的守恒方程,火焰两侧的特征线方程以及湍流燃烧公式可求出火焰两侧的参数。再根据管道两端的边界条件,利用 Rubin-Lax-Wendroff 格式进而求得不同时刻管内流场的结构。本文凭此对大型通道中的粉尘爆炸进行了数值模拟和讨论。

大型通道刚性支撑与侧模早拆体系施工技术

针对建筑内部或穿越连廊下部的大型通道,研发一套大型通道支撑体系及防撞技术和新型楼板模板早拆体系,实现通道安全及满足人员密集处的交通需求。阐述刚性支撑体系和两侧模板早拆体系的方案与原理,以及整个技术方案的实施过程,以期为同类工程提供参考。

大型跨海通道海上施工防台风应急管理与对策探讨——以深圳至中山跨江通道为例

大型跨海通道高风险作业均为海上施工,海上施工极易遭受恶劣气候尤其是台风的破坏。海上防台风比陆地防台风在组织、预案、撤离、加固、转移、救援等方面更为艰巨。海上防台风应急管理是海上施工安全管理的一项极具挑战性工作。深中(深圳—中山)通道项目是继港珠澳大桥之后又一个极具挑战的世界级宏伟工程,集“桥、岛、隧、水下互通”于一体,是大型跨海通道海上防台风的典型项目。

大型地下输煤通道箱型基础整体施工技术

随着科技的进步,原来的地上式皮带栈桥已经影响到城市发展及环境保护要求,地下通道多为箱型基础,传统工艺面临的质量通病与渗漏问题很难根本避免,本文介绍的箱型基础整体施工方法很好的解决了这个问题。

年末买股 胜算九成

本周综指周K线以十字星报收,显示多空双方非常矛盾的心态。沪综指连续两周收于1300点以下,且近一个月以来的下跌趋势仍未扭转,大盘能否在笔者上周指出的中短期时间之窗形成关键逆转,下周的走势显得非常关键。以下就几个重要问题进行简单探讨:

Evoked membrane potential change in rat optic nerve fiber:Computer simulation

Objective The optic nerve is a key component regarding research on visual prosthesis.Previous pharmacological and electrical studies has pinned down the main features of the mechanisms underlying the nerve impulse in the rat optic nerve,and this work proposed a mathematical model to simulate these phenomena.Methods The main active nodal channels：fast Na^＋,persistent Na^,slow K^＋ and a fast repolarizing K^＋（A-current）were added on a double layer representation of the axon.A simplified representation of K^＋ accumulation and clearance in the vicinity of the Ranvier node was integrated in this model.Results The model was able to generate the following features.In the presence of 4-aminopyridine （4-AP）,spike duration increased and a depolarizing afterpotential（DAP）appeared.In the presence of 4-AP and tetraethylammonium（TEA）,the DAP was followed by a hyperpolarizing afterpotential（AHP）and the amplitude of this AHP increased with the frequency of the stimulation.In normal conditions（no drugs）：DAP and AHP were absent after a single action potential（AP）and a short train of AP;there was a relative refractoriness in amplitude lasting for 30 ms after an AP;an early AHP was revealed by a continuous depolarizing current;and there was a partial spike adaptation for a long current step stimulus.Conclusion The model successfully reproduced previous experiments results including long-lasting stimulation experiment,which is known to modify nerve physiological parameter values and is a key issue for visual prosthesis research.

Gas drainage from different mine of drainage systems for deep coal areas： optimal placement seams with high gas emissions

The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .

Improved dark channel image dehazing method based on Gaussian mixture model

To solve the problem of color distortion after dehazing in the sky region by using the classical dark channel prior method to process the hazy images with large regions of sky,an improved dark channel image dehazing method based on Gaussian mixture model is proposed.Firstly,we use the Gaussian mixture model to model the hazy image,and then use the expectation maximization(EM)algorithm to optimize the parameters,so that the hazy image can be divided into the sky region and the non-sky region.Secondly,the sky region is divided into a light haze region,a medium haze region and a heavy haze region according to the different dark channel values to estimate the transmission respectively.Thirdly,the restored image is obtained by combining the atmospheric scattering model.Finally,adaptive local tone mapping for high dynamic range images is used to adjust the brightness of the restored image.The experimental results show that the proposed method can effectively eliminate the color distortion in the sky region,and the restored image is clearer and has better visual effect.

Comparative identification of Ca～(2+) channel expression in INS-1 and rat pancreatic β cells

AIM： To identify and compare the profile of Ca^2＋ channel subunit expression in INS-1 and rat pancreatic β cells.METHODS： The rat insulin-secreting INS-1 cell line was cultured in RPMI-1640 with Wistar rats employed as islet donors. Ca^2＋ channel subunit expression in INS-1 and isolated rat β cells were examined by reverse transcription polymerase chain reaction （RT-PCR）. Absolute real-time quantitative PCR was performed in a Bio-Rad iQ5 Gradient Real Time PCR system and the data analyzed using an iQ5 system to identify the expression level of the Ca^2＋ channel subunits. RESULTS： In INS-1 cells, the L-type Ca^2＋ channel 1C subunit had the highest expression level and the TPRM2 subunit had the second highest expression. In rat β cells, the TPRC4β subunit expression was dominant and the expression of the L-type lC subunit exceeded the 1D subunit expression about two-fold. This result agreed with other studies, confirming the important role of the L-type lC subunit in insulinsecreting cells, and suggested that non-voltage-operated Ca^2＋ channels may have an important role in biphasic insulin secretion. CONCLUSION： Twelve major Ca^2＋ channel subunit types were identified in INS-1 and rat β cells and significant differences were observed in the expression of certain subunits between these cells.

世博轴，一路通世博

2010年上海世博会园区内将有一条千米长的大型通道,连接园区最大出入口和黄浦江畔的庆典广场,承担20%客流量进出园区,它就是世博轴。

Partial melting and crust-mantle interaction in subduction channels:Constraints from experimental petrology

It is proposed in the subduction channel model that the plate interface interaction is a basic mechanism for the mass and energy exchange between Earth’s surface and interior.The significant difference in composition and nature between continental lithosphere and oceanic lithosphere inevitably leads to variations in deep physical and chemical processes as well as crust-mantle interaction products in these two settings.Many studies of experimental petrology have provided constraints on the potential partial melting and crust-mantle interaction in oceanic subduction channels for silicate and carbonate rocks.The partial melts of mafic and felsic compositions are adakitic or non-adakitic granitic melts depending on melting pressure or depth.A trivial amount of CO2 can lower significantly the melting temperature of peridotites and lead to pronounced enrichment of incompatible elements in carbonate melt.The silica saturated or unsaturated melts can react with mantle-wedge peridotites in subduction channels to generate complex products.However,the existing experiments are mostly dedicated to island arc settings above oceanic subduction zones rather than dehydration melting above continental subduction zones.It is crucial to conduct high pressure and high temperature experiments to investigate all possible reactions between peridotites and crustal materials and their derivatives under the conditions responsible for the slab-mantle interface in continental subduction channels.Experimental results,combined with natural observations,are possible to elucidate the processes of metamorphic dehydration,partial melting and mantle metasomatism in continental subduction channels.