基于LDA的均直巷道断面风速分布规律实验研究

针对传统井下测风方法以及传统接触式流速测量方法的局限性,以矩形均直巷道断面风速实验测试为例,利用非接触式测试技术激光多普勒测速仪(LDA)对断面风速进行实验测试。实验表明:在平均风速为3m/s左右的均直巷道内的稳定流动下,断面风速分布近似呈矩形环状封闭波动曲线,测点风速具有极度的脉动现象,但测点速度大小服从正态分布。在不同断面平均风速下,断面轴线上风速分布均近似服从指数函数形式。研究表明,LDA测试技术能够较好的反映实验巷道流场风流湍流脉动特性,可以作为研究矿井通风一系列复杂流动的实验手段。

均直巷道通风能量耗散机理

为了深化对风流能量耗散的认识,基于流体力学相关原理,以均直巷道内稳定流动的风流为研究对象,首先分析了巷道风流分别为层流和湍流时的能量耗散,并指出了两者的异同,然后分析了平板间流体和圆筒壁间流体能量耗散,找到了无旋流动和有旋流动的本质,最后从细观角度对巷道风流层流流动和湍流流动(通风)的能量耗散产生原因及形成机理进行了分析,建立了巷道各项参数与通风能量耗散间的关系,特别分析了涡在湍流核心区能量耗散中的作用。发现单位长度巷道的层流能量耗散率与平均风速的平方及风流的动力黏度成正比,与巷道半径无关;单位长度巷道的湍流能量耗散率与平均风速的立方、沿程阻力系数、巷道半径及空气密度成正比。不论何种流体运动,从局部来看,其单位体积能量耗散率等于流体动力黏度与剪切速度梯度的平方的乘积。湍流流动与层流流动的本质区别在于,湍流中存在的涡旋使得局部剪切速度梯度增大,能量耗散率随之增大。湍流核心区能量耗散与巷道平均风速的立方成正比关系,是由于涡的初始动能与速度平方成正比,产涡频率与速度成正比。随着巷道壁面粗糙度的增大,层流底层边界上产生的涡的半径、初始动能及湍流核心区能量耗散也随之增大。

计及多类装置协同的直流偏磁治理设备全局优化配置研究

随着交直流电网规模及运行复杂性的增加,直流偏磁现象日益呈现多发和超标变压器不确定的新特点,考虑到隔直装置的投资运维成本高昂、占用变电站额外空间,且直流偏磁往往不是高发事件,遍历所有偏磁可能性并对超标变压器均加装隔直设备并不合理,基于有限数量隔直设备实现受影响区域的直流偏磁全局优化治理势在必行。结合近年来提出的性价比较好的均直设备,该文提出一种基于隔直/均直装置协同的偏磁治理设备全局优化配置方法,力图在治理效果和投资运行成本上取得平衡。首先,以所有工况下中性点电流最大值最小和投资成本最低为目标,采用量子遗传算法进行多目标优化,得到偏磁治理设备的可选配置方案集;继而引入继电保护可靠性及对交流拓扑适应性两种校核手段,对优化所得Pareto解集(可选方案集)进行进一步筛选,最终确定最佳的混合配置方案。以宜昌电网为例,仿真对比了传统治理方法与所提方案的综合效果,验证了所提方案的有效性及优越性。

基于并联可调电阻组的直流偏磁柔性治理策略

基于隔直电容的偏磁治理方法容易加速其他企事业单位敷设于地中的金属管道的腐蚀,造成难以调解的责任冲突。同时,由于缺乏对电流全局分布的考虑,传统隔直投切方法也容易造成区域内其他变压器出现中性点直流电流被动超标的现象。因此,首先提出了均直的概念,并设计了一种基于可调并联电阻组的均直装置,其次以此为抑制工具,结合交流系统等效电阻网络、变电站与接地极地理位置分布情况,建立全局均直装置优化投切数学模型。最后以全局中性点直流电流最大值最小为目标进行寻优,得到最优投切方案,实现对直流偏磁的柔性治理。通过采用宜昌地区电网实际参数对比了所提方法与传统方法的隔直效果,验证了所提方法的有效性及优越性。

随机介质中的波动问题研究

本文提出采用随机有限元方法研究随机介质中的汉动问题，以一半无限均直剪切梁为例分析了考虑介质随生时梁的反应。应用本文方法，可在分析波传播的同时考虑复杂介质的随机性。

A fracture enhancement method based on the histogram equalization of eigenstructure-based coherence

Eigenstructure-based coherence attributes are efficient and mature techniques for large-scale fracture detection. However, in horizontally bedded and continuous strata, buried fractures in high grayscale value zones are difficult to detect. Furthermore, middleand small-scale fractures in fractured zones where migration image energies are usually not concentrated perfectly are also hard to detect because of the fuzzy, clouded shadows owing to low grayscale values. A new fracture enhancement method combined with histogram equalization is proposed to solve these problems. With this method, the contrast between discontinuities and background in coherence images is increased, linear structures are highlighted by stepwise adjustment of the threshold of the coherence image, and fractures are detected at different scales. Application of the method shows that it can also improve fracture cognition and accuracy.

Evolution of secondary phases and properties of 7B04 aluminum alloy during DC homogenization

The effects of the direct current （DC） on the evolutions of hardness and morphology of the secondary phases in 7B04 aluminum alloy homogenized at 380？465 ℃ for 2 h were investigated in detail by electric conductivity measurement, hardness test, X-ray diffraction analysis, field emission scanning electron microscopy and energy dispersive spectrometry. The results show that with increasing temperature from 380 to 465 ℃, the electric conductivity of normal homogenized sample decreases from 34.9%IACS to 28.7%IACS, the hardness increases from HV 96 to HV 146, and the area fraction of secondary phase reduces from 4.5% to 1.89%. While, DC homogenized sample has a higher hardness, a lower electric conductivity and a smaller area fraction of secondary phases at the same temperature. The DC enhances the homogenization process by promoting the diffusibility of the solute atoms and the mobility of vacancy.

Microscopic Structure of Rabbit Hair

[Objective] The paper was to explore the microscopic structure of rabbit hair. [Method] Single rabbit hair with typical features was selected to observe its mi- croscopic structure from tip to root, and its fiber diameter was also measured. [Result] The rabbit hair tip was constituted by scale layer and cortical layer, without medullary layer; the middle part was generally constituted by scale layer, cortical layer and medullary layer; the root had no medullary layer, and the scale layer was wheatear-shaped. This was the property of rabbit hair, which could be used for comparative studies with other animal fiber and species identification. Rabbit hair had developed medullary layer, and fiber diameter was positively related to column number of medullary cavity. The hair generally was single column, and coarse hair was multi-column. Single rabbit hair was the finest in the tip, coarse in the middle and tapering in the root. The diameter difference of various parts was large, and the ex- ternal growth characteristics was spindle-shaped. [Conclusion] Using biological micro- scope method to identify different animal fur and product species is more objective and simple.

Determination of Geopotential of Local Vertical Datum Surface

This paper first develops the approaches to determine the geopotential of the local mean sea level,and then investigates the offset of the 1985 vertical datum surface defined by the mean sea level of Yellow Sea at the Dagang Tide Gauge in Qingdao city using the developed approaches and GPS/leveling data.It shows that the geopotential of the local mean sea level at the tide gauge is equal to 62 636 853.5±0.2 m2·s -2 and that the 1985 vertical datum surface is 24.6±5.4 cm above the geoid realized by the geopotential W 0= 62 636 856.0±0.5 m2·s -2.

An improved mean shift tracking algorithm based on double weighted color histogram

In practical application,mean shift tracking algorithm is easy to generate tracking drift when the target and the background have similar color distribution.Based on the mean shift algorithm,a kind of background weaken weight is proposed in the paper firstly.Combining with the object center weight based on the kernel function,the problem of interference of the similar color background can be solved.And then,a model updating strategy is presented to improve the tracking robustness on the influence of occlusion,illumination,deformation and so on.With the test on the sequence of Tiger,the proposed approach provides better performance than the original mean shift tracking algorithm.

Surgical outcome of pancreatic cancer using radical antegrade modular pancreatosplenectomy procedure

AIM:To evaluate the surgical outcomes following radical antegrade modular pancreatosplenectomy (RAMPS) for pancreatic cancer. METHODS:Twenty-four patients underwent RAMPS with curative intent between January 2005 and June 2009 at the National Cancer Center, South Korea. Clinicopathologic data, including age, sex, operative findings, pathologic results, adjuvant therapy, postop-erative clinical course and follow-up data were retro-spectively collected and analyzed for this study. RESULTS:Twenty-one patients (87.5%) underwent distal pancreatectomy and 3 patients (12.5%) underwent total pancreatectomy using RAMPS. Nine patients (37.5%) underwent combined vessel resection, including 8 superior mesenteric-portal vein resections and 1 celiac axis resection. Two patients (8.3%) underwent combined resection of other organs, including the colon, stomach or duodenum. Negative tangential margins were achieved in 22 patients (91.7%). The mean tumor diameter for all patients was 4.09 ± 2.15 cm. The 2 patients with positive margins had a mean diameter of 7.25 cm. The mean number of retrieved lymph nodes was 20.92 ± 11.24 and the node positivity rate was 70.8%. The median survival of the 24 patients was 18.23 ± 6.02 mo. Patients with negative margins had a median survival of 21.80 ± 5.30 mo and those with positive margins had a median survival of 6.47 mo (P = 0.021). Nine patients (37.5%) had postoperative complications, but there were no postoperative mortalities. Pancreatic fistula occurred in 4 patients (16.7%):2 patients had a grade A fistula and 2 had a grade B fistula. On univariate analysis, histologic grade, positive tangential margin, pancreatic fistula and adjuvant therapy were significant prognostic factors for survival. CONCLUSION:RAMPS is a feasible procedure for achieving negative tangential margins in patients with carcinoma of the body and tail of the pancreas.

Compocasting of A356-CNT composite

A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and hardness were examined.In order to alleviate the problems associated with poor wettability, agglomeration and gravity segregation of CNTs in the melt, CNTs were introduced into the melts by injection of CNT deposited aluminum particles instead of raw CNTs.Aluminum particles with mean diameters of less than 100 μm were first deposited by CNTs using Ni-P electroless plating technique and then injected into the melt agitated by a mechanical stirrer.The slurry was subsequently cast at temperatures corresponding to full liquid as well as 0.15 and 0.30 solid fractions.The results show that addition of CNTs to A356 matrix can significantly refine both full liquid and semi-solid cast microstructures.Hardness of the samples is also significantly increased by addition of CNTs and A356-CNT composite cast at 0.3 solid fraction produces the highest hardness.

Unusual histopathological findings in appendectomy specimens:A retrospective analysis and literature review

AIM: To document unusual findings in appendectomy specimens. METHODS: The clinicopathological data of 5262 patients who underwent appendectomies for presumed acute appendicitis from January 2006 to October 2010 were reviewed retrospectively. Appendectomies performed as incidental procedures during some other operation were excluded. We focused on 54 patients who had unusual findings in their appendectomy specimens. We conducted a literature review via the PubMed and Google Scholar databases of English language studies published between 2000 and 2010 on unusual findings in appendectomy specimens. RESULTS: Unusual findings were determined in 54 (1%) cases by histopathology. Thirty were male and 24 were female with ages ranging from 15 to 84 years (median, 32.2 ± 15.1 years). Final pathology revealed 37 cases of enterobiasis, five cases of carcinoids, four mucinous cystadenomas, two eosinophilic infiltrations, two mucoceles, two tuberculosis, one goblet-cell carcinoid, and one neurogenic hyperplasia. While 52 patients underwent a standard appendectomy, two patients who were diagnosed with tuberculous appendicitis underwent a right hemicolectomy. All tumors were located at the distal part of the appendix with a mean diameter of 6.8 mm (range, 4-10 mm). All patients with tumors were alive and disease-free during a mean follow-up of 17.8 mo. A review of 1366 cases reported in the English literature is also discussed. CONCLUSION: Although unusual pathological findings are seldom seen during an appendectomy, all appendectomy specimens should be sent for routine histopathological examination.

Experimental investigation of particle-induced pressure loss in solid–liquid lifting pipe

In order to investigate the characteristics of particle-induced pressure loss in the solid–liquid lifting pipe,a series of experiments were conducted in 200 mm diameter lifting pipe.Simulation manganese nodules with five different mean diameters of10 mm,20 mm,30 mm,40 mm and 50 mm were used,both in isolation and a combination in equal fraction by mass.The flow velocities in the lifting pipe ranged from 0.12 m/s to 1.61 m/s,and the mass of particles employed was 10 kg for each particle diameter.Three regimes,wavy bed,partly fluidization,and fully fluidization,were observed over the flow velocity.The solid–liquid pressure drop data were measured by differential pressure transmitter,and pressure drop caused by the solid particles was calculated and analyzed.The results show that the evolutions of the pressure loss due to solid particles are relevant to the solid–liquid flow regimes,and they are distinctly influenced by fluid velocity and particle size.

Effect of heat treatment of Mn-Cu precursors on morphology of dealloyed nanoporous copper

Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method. The effects of heat treatment of Mn-Cu precursors on alloy phase, morphology and composition of the resultant nanoporous copper were investigated. It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors, which consequently results in a more fully dealloying for forming nanoporous copper. The alloy phase changes from Cuo.a9Mno.51 and Cuo.21Mno.79 of non-thermally treated precursor to Cuo.33Mn0.67 of heat treated alloy. The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04% （molar fraction） made from the precursor without and with 95 h heat treatment. The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones： the uniform bi-continuous structure zone and the blurry or no pore structure zone. Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor, and the average ligament diameter is 40 nm, far smaller than that from the non-thermally treated precursor, in which the average ligament diameter is estimated to be about 70 nm.

Prediction of Effective Diffusion Coefficient in Rotating Disc Columns and Application in Design

A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.

Effect of Biodiesel Soot on Tribological Behavior of Liquid Paraffin

Biodiesel soot （BDS） was collected from the combustion of biodiesel using a self-made soot trap. The effect of BDS on the txibological behavior of liquid paraffin （LP） was investigated using a four-ball txibometer. A rotating viscometer was used to investigate the effect of BDS on the viscosity of LE The morphology, composition, and tribological mechanism of BDS were studied by means of FETEM, XRD, XPS, SEM/EDS, and the 3D laser scanning microscopy. Test results showed that the BDS aggregates were chain-like, and the average diameter of BDS was 35 nm. The BDS existed in the form of graphitic layers and amorphous carbon. The oxygen-containing functional groups in BDS consisted of the （C-O-C） and （C-O-H）. With an increasing BDS content, the dynamic viscosity of LP increased and the maximum non-seizure load increased initially and became stable later. In addition, the average wear scar diameter （AWSD） of LP increased and the average friction coefficient of LP decreased at first and then increased later. The tribological mechanisms could be ascribed to the variation in content of BDS： BDS could act as a friction modifier for a lower friction coefficient in case of low BDS content. However, the BDS aggregates could lead to increase of abrasive wear to influence the lubricating oil film at higher content of BDS, which would reduce the friction reduction ability and wear resistance of LP.

Structure of the organic crystallite unit in coal as determined by X-ray diffraction

X-ray diffraction （XRD） was used to study the structure of the organic crystallite unit （La, Lo doo2） in coals collected from Henan and Shanxi Provinces. XRD patterns of coal were collected in a step-scan mode （0.1 °/step） over an angular range of 2-90° （20）, allowing 8 s at each step. The structure of the crystallite unit was determined from the Scherrer equation and peak parameters deduced from whole pattern fitting. The results show that the structure of the crystallite unit in coal is mainly controlled by the coal rank. As the coal rank increases the average diameter of a coal crystallite unit （La） increases, the interlayer spacing （doo2） decreases slightly, and the average height of a coal crystallite unit （Lc） increases at first but then decreases. A new diffraction peak from the crystallite unit in coal was found at a low scattering angle in the XRD pattern （2-10~）. This suggests a structure with an inter-layer spacing from 1.9 to 2.8 nm exists in coal crystallites.

Development of a continuum robot for colonoscopy

A novel continuum robot for colonoscopy is presented.The aim is to develop a robot for colonoscopywhich can provide the same functions as conventional colonoscope,but much less pain and discomfort forpatient.In contrast to traditional rigid-link robot,the robot features a continuous backbone with nojoints.The continuum robot is 300 mm in total length and 12 mm in diameter that is less than the averagediameter of human colon(20 mm).The robot has a total of 4 DOF(degrees of freedom)and is actuatedremotely by 6 hybrid step motors through super-elastic NiTi wires.Its shape can be changed with highdexterity,therefore ensuring its adaptability to the tortuous shape of human colon.The mechanical struc-ture,kinematics and DSP-based control system are discussed; prototype experiments are carried out tovalidate the kinematics model and to show the motion performances.

Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

Broodstock of Verasper moseri （Jordan and Gilbert） aged 3-4 years old were selected, and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions. Fertilized eggs were obtained by artificial fertilization, and the development of embryos, larvae and juveniles was observed continuously. The results showed that the fertilized eggs of V. moseri were spherical, with transparent yolk and homogeneous bioplasm, and had no oil globule inside. The average diameter of the eggs was 1.77＋0.02 mm. The eggs of V. moseri were buoyant in water with salinity above 35. The cleavage type was typical discoidal. Young pigment cells appeared when olfactory plates began to form. Hatching occurred at 187 h after fertilization at a water temperature of 8.5℃. The newly hatched larvae, floating on the water surface, were transparent with an average total length of 4.69±0.15 mm. During the cultivation period, when the water temperature was raised from 9 to 14.5℃, 4-day old larvae showed more melanophores on the body surface, making the larvae gray in color. The pectoral fins began to develop, which enabled the larvae to swim horizontally and in a lively manner. On days 7-8, the digestive duct formed. The yolk sac was small and black. The yolk sac was absorbed on day 11. Larvae took food actively, and body length and body height clearly increased. The rudiments of dorsal and anal fin pterygiophores were discernible and caudal fin ray elements formed on day 19. On day 24, the larval notochord flexed upwards, and the rays of unpaired fins began to differentiate. Pigment cells converged on the dorsal and anal fin rays, and the mastoid teeth on the mandible appeared. On day 29, the left eyes of juveniles began to move upwards. Depigmentation began in some juveniles and they became sandy brown in color on day 37. Most juveniles began to settle on the bottom of the tank. The left eyes of juveniles migrated completely to the right side on day 50, when the average body length attained 2.5±0.18 cm, and juveniles accomplished metamorphosis to young. The embryonic and larval characters of several flounder species are compared.