Search

In this paper, the high temperature flow behaviors of 6061 Al alloy was studied by thermal compression experiments. The effects of temperature, strain rate and strain on the microstructure evolution and flow behavior of the alloy were investigated by experiments. The results show that the flow stress of the alloy increases with the increase of strain rate and it decreases with the increase of deformation temperature. The flow curve reaches the dynamic equilibrium under the interaction of work hardening and dynamic softening mechanism. The uprising deformation temperature promotes thermal excitation dynamic recrystallization of deformed microstructure. With the increase of strain, the microstructure of the alloy is transformed from equiaxed crystal morphology to fibrous structure and strain-induced dynamic recrystallization occurs. As strain rate increases, the action time of dynamic softening mechanism for the studied alloy is reduced, resulting in the fraction of dynamic recrystallized structure is reduced and the flow stress increases.

Deep-hole machining is an important part in the field of mechanical processing of diesel engine. Gun drill has been widely used in deep-hole machining because of its high dimensional accuracy, high efficiency and good straightness. Through experiments on drilling compacted graphite iron with two different edge types of double-edged gun drills, the spindle power, axial force and tool wear were analyzed and found out one edge type which is more suitable for processing compacted graphite iron. This paper presents a simulation of deep hole drilling to validate the analysis. The research results have important guiding significance for deep hole processing of compacted graphite iron.

Cutting force and cutting temperature are two important parameters in the cutting processes. In this paper, AdvantEdge finite element analysis software was used to simulate and analyze the reaming process of aviation aluminum alloy 7050 by using PCD reamer. The cutting simulation model was established to investigate the effect of spindle speed, feed per tooth on thrust force and cutting temperature. Simulation results showed that the cutting force increased with the increase of feed per tooth at different spindle speeds. And in the case of different feed per tooth, the cutting force decreased slightly as the spindle speed increase. Besides, from the cutting temperature distributed in the reamer, the cutting temperature near the tip of the tool in the reaming process was highest, the cutting temperature increased with the increase of both spindle speed and feed per tooth.

Cutting temperature is one of the most important parameters in the cutting process, which has an important influence on the machining accuracy of workpiece, the power consumed by the machining and the degree of tool wear. There are many factors influencing the cutting temperature, such as the properties of workpiece materials, geometric parameters of the tool, the use of cutting fluid and so on. In this paper, we used orthogonal experimental method, with titanium alloy TC18 as the carrier and AdvantEdge as the simulation platform, established the cutting simulation model. With the cutting temperature as the optimization goal, the geometric parameters of the cemented carbide reamer are optimized.

In deep hole machining, drilling parameters for twist drills have an important impact on tool life and economic efficiency. In order to explore the influence of drilling parameters on twist drills, this paper established a drilling model for twist drill 45 steel, orthogonal experiments were designed. AdvantEdge FEM finite element software was used to simulate the drilling force, torque and drilling temperature. The drilling force, torque and drilling temperature were analyzed by using the finite element simulation value as the orthogonal experimental value. In order to ensure that the simulation results have certain reference value, the drilling experiment was carried out in order to ensure the simulation results have reference value. Finally, the optimal combination of drilling parameters was obtained.

Reaming is one of the finishing processes that has been widely applied in automotive industry. Reaming parameters were evaluated and optimized based on multiple performance characteristics including tool wear and hole quality. Taguchi’s L16, 4-level, 2-factor orthogonal array (OA) was conducted for this test. It was shown that crater wear and flank wear were seen on the tool surface. Furthermore, the crater wear was also of major significance. Hole quality was discovered to be mostly dependent upon cutting speed and feed rate. TiAlN coated carbide reamer shows the best performance with respect to the tool wear as well as hole quality. Grey relational analysis used as a multiple-response optimization technique found that feed rate was the more influential parameter than cutting speed. The goal of the experimental results was to obtain both minimum diametral error and the value of surface roughness by adopting the optimal combination of the reaming parameters.

Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. After implantation into human blood vessels, the vascular stent can be continuously degraded over time and eventually disappear completely after the treated blood vessels are healed and support from the vascular stent is not needed. The vascular stent materials used in clinic should have good biocompatibility, which mainly involves blood compatibility and cell compatibility. In terms of cell compatibility, the influence of materials on cell growth should be observed. The various biological materials should have good anticoagulant character, so as to reduce the tendency of thrombosis and avoid the occurrence of various risk events in clinical treatment.

Biodegradable vascular stent is mainly made of materials that can be naturally decomposed. Magnesium and its alloys have excellent mechanical properties and biocompatibility. The vascular stent made of magnesium and its alloys has the unique advantages of strength of metal scaffolds and bioabsorbability of degradable polymer scaffolds. Due to the special microenvironment inside the blood vessels, the stent should have good resistance against corrosion. After implantation of metal materials for human tissue repair, the surface oxidation film spontaneously formed in the air will react with the human physiological environment. The nature of the interface between materials and tissues will have a certain impact on the corrosion resistance of metals and the degree of metal ion release, thus determining the biocompatibility of materials.

Cu-based friction materials were prepared by powder metallurgy technology. The effect of Fe content on friction and wear properties of Cu-based friction materials has been investigated. The results indicate that Fe content has great effects on the wear ability of Cu-based friction materials. Fe works as frictional component in copper-based friction materials, influening the mechanical and frictional property of materials. With increasing Fe content, the hardness and friction coefficient of Cu-based friction materials stability increase, the wear rate of the friction materials decreases. When Fe content is 6%, the materials posses stably high friction factors, as well as good wear ability.

Considering the S-vacancy defect in single-layer MoS2, the metal doped including Fe-, Co-, Cu-, Zn-, doped specimens in MoS2 single-layer and their effect of the adsorption and diffusion of Li on the MoS2 single-layer were investigated by Density Functional Theory (DFT). Under Mo-rich condition, the Fe-, Co-, Cu-, Zn-doped specimens by substitution of S atom have smaller formation energy than those under S-rich condition. For doped MoS2 single-layer, lithium donates electron to doped specimens, making the band level of the doped specimens downward into the valence band and the Fermi energy level further upward. The Li ion has positive charge, the ion adsorptive property was enhanced because of strong coulomb interaction. These are confirmed by the large adsorption energies (-1.11 ~ -0.44 eV). The diffusion energy barriers except for the path closest doped specimens by substitution of S atom are ~ 0.25, which are similar to that of pristine one. Above all, the metal doped by substitution of S atom MoS2 single-layer are promising anode materials of LIBs.

The Super Cascode is a series connected structure with a normally-off low voltage Si-MOSFET and multiple normally-on wide bandgap semiconductors. It has low switching losses compared with silicon based bipolar devices, and low on-resistance and low cost compared with other single high voltage normally-off wide bandgap semiconductor devices. In practice, however, there are inevitable parasitic inductances, which result in the increase of switching losses. The method is proposed to eliminate the common-source inductances (CSIs), such as using stack-die configuration with each device and adding an additional inductance in the gate loop of Si-MOSFET. It is numerically shown that the rise and fall times of the proposed method were 33.5% and 7.2% faster than the conventional one, respectively.

The wear resistance of a Cr19Mn19Mo2N0.7 stainless steel treated by solution treatment 1160°C for 6h then aging at 900°C for different times is investigated in this paper. Microstructures are analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). A fingerprint nitride (Cr2N) structure is formed during aging, which first nucleates within ferrite laths and along the austenite grain boundaries, and then grows into austenite with increasing aging time. It is shown from the laboratory wear test that the optimum wear resistance is obtained through a solution treatment at 1160°C for 6h and aging at 900°C for 3h, which is mainly attributed to a moderate amount of fingerprint nitrides formed within ferrite laths.

The characteristics of cutting forces vibration and its effects to the hole quality in reaming aluminum cast alloy using a poly-crystalline diamond (PCD) step reamer in dry and wet conditions were studied. First, centrifugal force vibration model of the PCD step reamer during machining process was established and through the analysis of the model, it can be concluded that the maximum amplitude of the vibration is positively related to the angular velocity of the reamer. Then, thrust force and cutting torque were measured by a Kistler Dynamometer during reaming process and these vibration frequency and amplitude were analyzed by fast Fourier transformation (FFT). Hole quality was evaluated by hole diameter and surface roughness. Results show that, as the spindle speed increases, the stability of thrust force and cutting torque deteriorates gradually, and there was a severe vibration in the cutting force and the surface roughness when the spindle speed reached 10000 rpm in wet and 7000 rpm in dry cutting conditions. Compared the variation of hole surface roughness and vibration characteristic of cutting forces, it can be observed that the trends are very consistent, the surface roughness deteriorates when cutting forces become unstable. Therefore,the cutting forces stability was an important factor that influence the hole quality. Cutting fluid has a positive effect to stabilize the reaming process and was beneficial to improve the hole quality.

Cutting performance of reaming alloy gray cast iron HT250 using carbide, cermet and CBN reamers was studied. Experiments were conducted under constant cutting parameters and cooling strategy. Tool life, hole diameter, spindle power, surface roughness and tool wear were analyzed. The hole diameter and spindle power would keep steady when reaming with carbide reamer after 400 holes to the tool life of 1050 holes. But holes diameter reduced and spindle power increased with the number of machined holes increasing during the whole tool life when using cermet or CBN reamer. The surface roughness Rz of the holes reamed by carbide reamer was within the tolerance, although it was worse than that reamed by cermet and CBN reamer. It can be summarized that the carbide was the most suitable material for reaming alloy gray cast iron because of the longest tool life, steady hole diameter and spindle power, qualified surface roughness. After machining, crater wear and clearance wear were produced on the cermet and CBN reamer, which were caused by abrasive wear. In addition, flaking and breakages appeared on the edge of cermet reamer, which were not found on CBN reamer. However, the clearance wear of carbide reamer was smaller than that of CBN reamer, and built up edge was found along the cutting edge.

Cutting force is one of the most important parameters in the machining process, it significantly influenced machining precision of the workpiece, power consumed in the machining process, wear of the cutting tools and so on. There are many factors that affect the cutting force, such as the performance of the workpiece material, cutting speed, usage of the cutting fluid, etc. Single factor variable method was used in this paper, RuT450 was used as workpiece, welded cemented carbide gun drill was used as cutting force and LS-DYNA was used as simulation platform to established the cutting simulation model to analyzed the impact of the cutting speed and feed rate to the drilling force. Simulation results show that, at the low speed drilling stage, drilling force increases with the increase of the feed rate and decreases with the increase of the rotation feed, from the stress cloud it could be seen that the equivalent stress near the drill tip reached the maximum in the drilling process.

In order to study the milling process of compacted graphite iron cylinder block in practical, cutting parameters optimization experiment was conducted when cutting parameters were set as independent variable, and cutting efficiency and spindle power were set as optimization objective. The results showed that spindle power increased as the cutting speed and feed per tooth increasing, but cutting torque increased initially and then decreased as the cutting speed increasing. Feed force decreased with the increasing cutting speed and decreasing feed per teeth. Matlab software was used to optimize the cutting parameters when cutting efficiency and empirical formula of spindle power were settled as the objective functions. The most suitable parameters were abtained as V=164m/min and fz=0.28mm/z. The tool rake face mainly took place crater wear and material sticking. The main wear mechanisms for rake wear and fland wear were abrasive wear and adhesion wear.

Fiber-reinforced ceramic composites are relatively promising materials in aerospace and other high-tech area. In this work, the grinding mechanism of 2.5-dimensional woven quartz fiber-reinforced ceramic matrix composites was researched by experimental analysis. The acoustic emission (AE) combined with wavelet analysis was adopted to evaluate the grinding process. The ratio of energy which may indicate the mode of fracture of the composites was used for analyzing each of the AE signals levels. The effects of meso-structure on AE frequency distribution have been discussed. It was found that that specific frequency band is corresponding to the specific fracture mode, such as fiber fracture, interface debonding and matrix fracture. It indicates that grinding mechanism is highly dependent on the meso-structure of the composites.

By adjusting mass fraction of Ni-Al composite additive in Ti-B4C primary system, a series of TiB2-based ceramic composites were prepared by combustion synthesis in high gravity field. Because the adiabatic temperature of the whole reaction system maintained a constant in the presence of mass fraction of Ni-Al additive smaller than 18.55%, increasing mass fraction of Ni-Al additive to be 15% brought about the improved homogeneity in refined microstructure of the enhanced-densification TiB2-based composite, so flexural strength and fracture toughness of the ceramic composite increased simultaneously due to the enhanced self-toughening mechanisms contributed by a number of fine TiB2 platelets.

The variation rate of seed-spaces in soil is higher and the qualification rate is lower due to the high seed releasing position of double discs furrow opener of no-tillage planter. To solve this problem, a new belt-type device for air-suction metering was designed and its main structural parameters was determined based on the cavitation time analysis of seed meter. This device integrated both transmission mechanism and seed releasing mechanism into one system, matching with the rotating speed of seed disc and the walking velocity speed of planter. The optimal parameters in relating to seeding performance were obtained by orthogonal test. When the seed releasing height is 100 mm, the rotational speed of seed disc is 30 r/min and the pressure of negative room is 3.5 kpa, the qualification rate of seed-space, the missing rate and multiple rate of seed per hill can be 98.5%, 0.48% and 1.02%, respectively.

Jack-up platform jacking system which undertakes the weight of the platform and working load is very important during the lifting, and its performance exerts a direct influence on the safety and application effect of the whole platform. The super-modulus pinion and rack of jack-up platform jacking system are most likely to damage by fracture and fatigue pitting, which are due to the hostile environments. As a result of dynamic load, the analysis of dynamic contact has important engineering significance in an actual project. For strengthening the carrying capacity of pinion and shortening the design period, the research of carrying capacity factors is very meaningful. In this paper, the changing of stresses on the pinion and rack are gained by FEM, and main parameters that influence the carrying capacity of the pinion in a jacking system are analyzed according to the calculation method in GB standard. The study results shows the contact stresses and bending stress are higher throughout the meshing process, which implies the dangerous position of the pinion. In single meshing period, the trend of bending stress in the compression side of pinion and rack is opposite, while the bending stress in the tension side of both rack and pinion are minimum near the pitch circle. The carrying capacity of pinion can be strengthened by changing the main parameters, such as tooth width, normal modulus, pressure angle, modification coefficient, but the influence degree of each parameter is different.

The microstructure changes of acrylate spray-on waterproof material in alkaline groundwater environment were tentatively studied with X-ray microscopy (XRM), and the validity of deciding the failure of the material was explored in paper. Regarded NaOH solution with pH=12 as corrosive medium, after the immersion in the alkaline solution, spray-on waterproof material was scanned with XRM, and the structure was characterized with some indexes such as porosity and pore connectivity. The results show that when the waterproof material is immersed in alkaline solution for some time, the surface of the material becomes uneven, the overall porosity falls and the pore connectivity rises. It is feasible to study on the failure of waterproof material in underground engineering with XRM.

A novel topology circuit of active compensation was discussed to be used to manage negative sequence caused by locomotive load in electrified railway. The main circuit used a three-phase two-leg compensator as active elements of shunt hybrid active compensator topology. The number of switch device in this topology was reduced by comparing with three-phase full-bridge active inverter and the cost was lower. The simulation model was developed with SIMULINK. The simulating results indicates that the shunt hybrid active compensator can restrain the problem of negative sequence which generated by locomotive load, and reduces the effect of reactive power, negative sequence, improves electric energy quality and verifies the correctness of the proposed structure and control method.

The analysis is made for the modification of multi-walled carbon nanotubes and the mechanical properties and microstructure of the modified carbon nanotubes toughening DSP cement mortar, the existence and toughening effect of modified carbon nanotubes on the fracture surface of materials were analyzed. Results shows that, the surface of the carbon nanotubes in the sample is covered with cement hydration products, with the carbon nanotubes in drawing state on the fracture surface and both ends of the tube connected firmly with cement materials, thus carbon nanotubes improve the toughness of materials effectively.

Loss of gray level is a usual phenomenon in tone transformation of digital image. In order to improve the effect of tone transformation, original image is segmented into blocks, which consist of some pixels. In tone transformation, average value of gray levels, which belong to the pixels of every image block, is computed. According to the different average values of image blocks, different curve for the tone transformation is selected and the pixels of the block are processed correspondingly. If the transformation curves for the processing are enough, the loss of gray level is relative fewer. Although some of the gray levels of different image block are lost, but the lost gray levels of different image block are disperse and are not always coincident. Therefore, compared with the tone transform with one single curve for whole image, the loss of the gray level in image, which is transformed with block-segmentation and with different curves, is much fewer and the quality of processed image is relative better. The principle, as well as the algorithm is described, and the results of processed images are analyzed.

Along with the developing of color imaging technique, the application of digital multilevel imaging device increases, such as digital printing press, color printer, electronic engraver for gravure printing and so on. Based on multilevel halftoning technique, some important items, i.e. count of color element, area percentage of color elements, relationship between the percentages of color element and multilevel dots are studied and summarized. Finally, based on Neugebauer equation, a theoretical color model under the condition of multilevel halftoning is constructed.

Solute transport through riparian zone was studied experimentally and numerically with the consideration of silt layer. The silt layer had markable change on flow field and lead to a significant variation of the breakthrough curves (BTCs). BTCs of solute tracer tests show non-Fickian features as early arrival of peak value and long tailings. BTCs were fitted by advection dispersion equation (ADE), mobile and immobile model (MIM) and the continuous time random walk (CTRW) models. MIM and CTRW can fit BTCs better than ADE and MIM fit better on the capture of the peak value and CTRW fit better in description of the long tailing.

In digital signal processing system and microcomputer system, often need to high speed DSP devices and large-scale ASIC, FPGA to design and development, in these systems, the high requirement of the precision of the power module and power supply current, power supply module design will directly affect the stability of the whole system. In addition, the power supply module is usually low voltage large current of DC/DC converter, the requirement of efficiency is very high, generally over 90%. This paper introduces the FPGA based on TI company's TPS54810 power supply with low voltage large current DC/DC converter module design, this paper introduces in detail the external compensation of synchronous buck DC/DC converter power supply circuit design methods.

The nitrogen-doped diamond-like carbon film was prepared on Ti6Al4V alloy by using plasma enhanced chemical vapor deposition (PECVD) technique,and its biocompatibility was studied.The surface morphology,chemical composition and contact angle were measured by scanning electron microscope (SEM),X-ray photoelectron spectroscopy(XPS),Raman Spectrometer and contact angle measuring device. Finally, the proliferation rate and cellular morphology of 3T3-E1 osteoblast cells on different sample surfaces were tested and Image J software was used to statistically analyze the count of the adhered cells. The results showed that cell adhesion and proliferation were significantly (P

Relying on the construction of a deep underground reservoir, vibration effects of ground were studied from two aspects: the peak value of vibration velocity and the basic frequency of blasting seismic waves, and were compared with the blasting vibration effect on the flat terrain surface. Research shows that blasting seismic wave’ impact on the surrounding building is relatively small because of its high frequency for the blasting excavation of underground reservoir. The frequency distribution in vertical and horizontal direction with scaled distance is roughly the same. And the peak value of vibration velocity in vertical direction is greater than that in horizontal direction, so blasting vibration effect in vertical direction is bigger than that in horizontal direction.

In this investigation, nanoSchiff bases Cobaltic complex was synthesized and used as the initiator in the copolymerization of carbon oxide and propylene oxide (PO). The nanoCobaltic complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and pressure of CO2 on the synthesis of polycarbonate were described. The results show that nanoCobaltic complex could be successfully applied in the copolymerization of CO2 and PO. The optimum conditions of the polymerization, which include CO2 pressure of 30 bar, reaction temperature of 80 °C, and reaction time of 3 hours.

This paper makes the experimental experiment on adding rare earth elements cerium doped in diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, iron and nickel, the cobalt in diamond matrix is entirely with iron and the process route of rare earth doping is indicated. The performance of matrix composites with rare earth elements and free of rare earth elements is measured and the results obtained show that the flexural strength, the hardness and the impact ductility of matrix composites with rare earth elements are improved and the flexural strength increases by 10~62% over that of the composites free of rare earth elements, and the impact ductility by about 5% correspondently. We have successfully studied out the rare-earth diamond tool matrix composites replacing Co with Fe, bearing good practical service performance and low price, and have made corresponding diamond bit.

An anti-lost data security storage system for Smartphone has been proposed in this paper. The encryption key of data and the identity are stored in USBKey, so as to realize the physical separation of the encryption key and data, and the matching of USBKey and Smartphone. The System solves the problems of data recovery and backup in Smartphone after the phone is lost. The results indicate that the system has good data protection features, such as encryption and decryption fast, secure and reliable transmission, anti-lost, etc.

In order to improve the working life of engine blade and delay the crack initiation and propagation, the shot peening strengthening treatment is usually used to.This article discusses the significance and necessity of the engine blade after shot peening and introduces shot peening strengthening process parameters to the engine blade, maily explains the equipment for engine blade shot peening strengthening, and summarizes applications of engine blade of shot peening strengthening equipment.

The relative adsorption coefficient, a novel parameter was introduced to describe the dominant adsorption ability of ions in cation membrane for all vanadium redox flow battery instead of traditional selectivity coefficient. The parameter as a function of membrane property and vanadium ions in membrane was derived from the relative potential differences in membrane between an isothermal adsorption and an ideal equivalent adsorption. The adsorption isotherms of three kinds of commercial membranes were measured for VO2+/H+ electrolyte system. The results show the reasonable rules that the relative adsorption coefficients increase as the VO2+ contents are increased whereas decrease as the H+ contents are increased in electrolyte.

Hyperspectral image classification is difficult due to the high dimensional features but limited training samples. Tri-training learning is a widely used semi-supervised classification method that addresses the problem of lacking of labeled examples. In this paper, a novel semi-supervised learning algorithm based on tri-training method is proposed. The proposed algorithm combines margin sampling (MS) technique and differential evolution (DE) algorithm to select the most informative samples and perturb them randomly. Then the samples we obtained, which can fulfill the labeled data distribution and introduce diversity to multiple classifiers, are added to training set to train base classifiers for tri-training. The proposed algorithm is experimentally validated using real hyperspectral data sets, indicating that the combination of MS and DE can significantly reduce the need of labeled samples while achieving high accuracy compared with state-of-the-art algorithms.

One-against-rest (OAR) is a well known multiclassification structure, which is an extension from binary classifiers. It has shown its great potential in pattern recognition and hyperspectral data processing. However, existence of unclassified region limits its application. In this paper, a new multiclassifier based on OAR combined with one-against-one (OAO) structure is proposed. In the multiclassifier, OAO is used to classify the unclassified region to improve performance of OAR. At the same time, the formation of unclassified region is discussed, and the pattern of selecting classifiers for secondary classification on unclassified region is proposed. To compare secondary classifiers and prove the conclusion, other six classifiers are selected , which are decision tree (DT), minimum distance (MD) based on Euclidean distance, MD based on Euclidean distance with kernel function, MD based on Mahalanobis distance, spectral mapping classifier (SMC) and maximum likelihood classifier (MLC). The SVM is used for OAR, OAO and DT in experiment and a hyperspectral remote sensing image is used as testing samples.

With the development in virtual reality technology, it has been applied in kinds of fields, e.g. education and engineering. This article introduces the concept and basic features of virtual reality, the application of VR in education and engineering, the building procedures and the functions of the virtual system with the case of the virtual Storage Cavern system. The system is consisted of four parts which enables students to understand and grasp the basic operation, maintenance, and standard accident responses more effectively than other teaching methods.

Silicon film as a surface passivation layer is reported to reduce surface recombination on silicon nanowires (SiNWs) and thus enable to improve SiNW solar cell (SC) performance. A question yet to be answered regards the link between the silicon film assets and the solar cell performances. We investigated the effect of the properties of silicon films on the SiNWs SC performances by adjusting hydrogen dilution. Our results showed that the open-circuit voltage (Voc) and short-circuit current density (Jsc) of SiNWs SC increase until hydrogen dilution 10 and then decrease. An open-circuit voltage of 0.397 V and short-circuit current density of 18.42 mA/cm2 are achieved at optimized hydrogen dilution. Based on the analysis of silicon film properties we proposed that the increase of defect density with hydrogen dilution was the main cause for the deterioration of SiNWs SC performance.

To greatly develop carbon sequestration forestry, conduct carbon sequestration forestation, increase forest carbon sequestration, ensure reduction of forest carbon emission, is an important measure and a completely new work to actively deal with climate change. This paper introduces the development process and research trend of coupling effect of artificial carbon sequestration capacity and ecological environment, explores the coupling development modes, and the relations between function coupling and composition element coupling with the objective of further improving the construction of ecological civilization and ecological environment.

Flight duration is a key design issue for the monitoring applications based on the UAVs. Based on the assumption that UAVs often fly at a high altitude, the resolution of images captured by the UAVs is not high enough. Thus, the problem of positioning the UAV can be solved by image matching. When a UAV comes to a certain place that it has ever been to, there are the same objects in the images that it takes currently and a short time ago. We propose a text retrieval like method based on SIFT vectors for computation efficient in image matching. Experiments show that our method is good at discriminating between images taken at different places.

Due to the internal structure of red sandstone is loose, the influence factors of acoustic velocity are variety, it is necessary to make a quantitatively research on the influence factors. With the aid of the ultrasonic testing for the rock, p-wave velocity of red sandstone decreased with the increase of porosity under the condition of no coupling medium, when the porosity exceeded a certain value, its internal pores and fractures had a great influence on wave velocity. When the density of red sandstone was greater than 1.82 g/cm3, wave velocity changed little, while the density was less than 1.82 g/cm3, wave velocity decreased rapidly. Under water-solid coupling condition, the change of wave velocity and porosity had no obvious regularity, part of the specimens’ wave velocity decreased a bit, while some specimens’ wave velocity were slightly higher, but the amplitude were small; Under oil-solid coupling condition, longitudinal wave velocity changed significantly, the biggest percentage of increase was 46.3%, the average was 33%.

The infrastructures of power grid can be easily damaged by fire disasters. Monitoring the spatial variations in the vegetation fraction is significant to predicate the probability of a fire disaster. While each vegetation indices (VI) computing method tends to suit some problem better than others, and typically have different parameters and configurations to be adjusted before achieving optimal performance on a dataset, we focus on conjunction with many types of traditional VIs' computing methods to improve their performance. Experimental results show that the accuracy of vegetation fraction estimation based on our method is higher than by using any single vegetation indices.

Star tracker is an accurate autonomous attitude measurement equipment. Multi-channel star tracker has been widely used and the accuracy of multi-channel star tracker becomes an important issue to study. In order to study this issue, an error model of multi-channel star tracker is established and analysis of accuracy of multi-channel star tracker is carried out with the model. Simulation results show accuracy of multi-channel star tracker is much higher than the single channel ones. There is great potential to develop multi-channel star tracker in the future.

Using finite element software ANSYS/LS-DYNA, dynamic response of pile-soil-structure interaction (PSSI) system under blasting load was analyzed, and the effects of blasting load on surrounding buildings foundation and superstructure were studied. This can provide a reference for structural and seismic reinforcement under blast loading. The results show that the every floor’ acceleration of superstructure of PSSI system along the vertical direction is usually larger than the value along the horizontal direction under horizontal explosion load. Peak-acceleration along the vertical direction decreases from the lowest layer to the top and peak-acceleration along the horizontal direction decreases and then increases with the increase of layer. The top peak-shear stress of piles is larger than the tip of piles, and the distribution laws are inverted triangles. The maximum values of peak of pile-soil contact pressure are located on the top of the piles. With little change in height and contact pressure plummeted. Contact pressure increases more near the tip of the piles.

The present study was aimed to improve the method for detecting Mycobacterium tuberculosis complex recently reported on Letters in Applied Microbiology. Eriochrome black T (EBT) was added to the reaction system of LAMP, due to complexation of EBT with magnesium ions, the color of reaction solution was red at beginning, when the reaction was in process, the precipitate of magnesium ions and pyrophosphate ions formed, EBT lost magnesium ions, the color of reaction solution became sky blue from red gradually, and the method exhibits a high sensitivity of 8 fg/μL. The improved LAMP assay can detect Mycobacterium tuberculosis complex rapidly, sensitively and visually, the method developed in this study had solved the “bottleneck” in popularization and application of LAMP technology, which had not only avoided aerosol pollution but also solved the false positive problem caused by primer dimers.

This paper proposes an automatic control strategy of the strip width in cold rolling process. The prediction model for the exit strip width of each stand is established. In addition to the strip width variation of the incoming hot-rolled material between the measured and the pre-set values, the variations of the rolling force, tension, bending force and the roll shift amount of each stand are utilized to model and forecast the stand exit width deformation. Then, the model can be used to determine the compensation values of the different profile adjustment mechanism and the exit strip width can be controlled in high accuracy. In this way, the effect of the strip width variation of the incoming hot-rolled material and the fluctuation of the stand rolling process parameters on the exit strip width can be eliminated. Moreover, the feed-forward control of the strip width can reduce the incidence of abnormal situation, such as the strip breakage and off-tracking ,and improve the stability of the cold rolling process.

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

Oil is an important energy and chemical raw materials and strategic materials. Nowadays, the layered water injection test technology become the key factor of oilfield production. According to different types of formation and for the artificial fracturing injection wells, this paper studied the infinite boundary, uniform flow and vertical cracks well, infinite diversion vertical fractures and conductivity vertical fracture wells’ absorbent law. The method to do all of the above work is to solve the equation of dimensionless bottomhole pressure in different formation and boundary conditions. The indicating curve of infinite uniform flow formation, unlimited conduction and limited conduction vertical fractures wells are almost identical, which means that the type of vertical fracture has little effect on the indicate curves of injection wells.

Layered injection commissioning technology has become a key factor to the oil production. For different types of formations, the paper analyzes the absorbent law in different homogeneous formations with different boundary conditions. The paper also creates a composite reservoir model, and then describes changes of absorbent law under coupling effect. The method to do all of the above work is to solve the equation of dimensionless bottomhole pressure in different formation and boundary conditions.

This paper firstly analyzes the problems that exist in the cold rolling of steel industry. Secondly, a new approach is proposed to temper and straighten the strip steel based on the temper leveling mill, shortly, TLM. The required high quality of the wave, surface and mechanical properties can be achieved only with TLM. TLM holds the functions of both temper machine and straightening mill and can produce good quality strip steel, no only the waviness, mechanical properties, but also the surface quality. The usage of TLM can lower the cost of the production of tempering, straightening and equipment investment.Finally, the experiments are done and verify the validity of the approach.