Integrated high-performance and accurate shaping technology of low-cost powder metallurgy titanium alloys: A comprehensive review

The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.

Predicting the probability distribution of Martian rocks mechanical property based on microscale rock mechanical experiments and accurate grain-based modeling

The exploration of Mars would heavily rely on Martian rocks mechanics and engineering technology.As the mechanical property of Martian rocks is uncertain,it is of utmost importance to predict the probability distribution of Martian rocks mechanical property for the success of Mars exploration.In this paper,a fast and accurate probability distribution method for predicting the macroscale elastic modulus of Martian rocks was proposed by integrating the microscale rock mechanical experiments(micro-RME),accurate grain-based modeling(AGBM)and upscaling methods based on reliability principles.Firstly,the microstructure of NWA12564 Martian sample and elastic modulus of each mineral were obtained by micro-RME with TESCAN integrated mineral analyzer(TIMA)and nanoindentation.The best probability distribution function of the minerals was determined by Kolmogorov-Smirnov(K-S)test.Secondly,based on best distribution function of each mineral,the Monte Carlo simulations(MCS)and upscaling methods were implemented to obtain the probability distribution of upscaled elastic modulus.Thirdly,the correlation between the upscaled elastic modulus and macroscale elastic modulus obtained by AGBM was established.The accurate probability distribution of the macroscale elastic modulus was obtained by this correlation relationship.The proposed method can predict the probability distribution of Martian rocks mechanical property with any size and shape samples.

Accurate models and nutritional strategies for specific oxidative stress factors: Does the dose matter in swine production?

Oxidative stress has been associated with a number of physiological problems in swine,including reduced production efficiency.Recently,although there has been increased research into regulatory mechanisms and antioxidant strategies in relation to oxidative stress-induced pig production,it remains so far largely unsuccessful to develop accurate models and nutritional strategies for specific oxidative stress factors.Here,we discuss the dose and dose intensity of the causes of oxidative stress involving physiological,environmental and dietary factors,recent research models and the antioxidant strategies to provide theoretical guidance for future oxidative stress research in swine.

Why Is an Integral an Accurate Value?

The derivative and integral in calculus are both exact values. To explain this reason, the integration interval can be infinitely subdivided. The difference in area between curved trapezoids and rectangles can be explained by the theory of higher-order infinitesimal, leading to the conclusion that the difference between the two is an infinitesimal value. From this, it can be inferred that the result obtained by integration is indeed an accurate value.

Theory and Practice of High-Level Sprint Training Based on Accurate Sectional Timing

There is an obvious gap in sprint level at home and abroad,and there are different opinions on the reasons.According to the analysis,physical energy and its distribution in each segment are the main factors restricting the sprint performance in China.Different from middle and long-distance running,we must rely on accurate sectional timing technology to master the law of speed-physical energy change in the process of sprint.Each stage is an integral part of the whole dash process,and each part restricts each other.Each stage has a relative best achievement.Simply pursuing the optimal state of segment is not only not helpful to the final result,but also counterproductive.

The Study Dynamics of Accurately Targeted Poverty Alleviation

The accurately targeted poverty alleviation has gradually become one of the important research directions in the field of poverty research. The existing foreign and domestic studies concerning about the accurately targeted poverty alleviation are few and mainly focus on the aspects such as poverty object recognition, target for poverty alleviation, and fund embarking; a complete system has not yet been formed for the relevant studies. On the basis of analyzing and reviewing relevant studies on the accurately targeted poverty alleviation at home and abroad, a further research direction for the accurately targeted poverty alleviation is proposed in this paper.

Accurate Measurement of Raman Depolarization Ratio in Gaseous CO2

The Raman depolarization ratios of gaseous CO2 in the spectral range of 1240-1430 cm-I are determined with a sensitive photoacoustic Raman spectroscopy, and more accurate data compared to the literature results are presented. The precision of the obtained depolarization ratio is achieved by measuring and fitting the dependence of the PARS signal intensity on the cross angle between the polarizations of two incident laser beams.

Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

An improved algebraic reconstruction technique（ART） combined with tunable diode laser absorption spectroscopy（TDLAS） is presented in this paper for determining two-dimensional（2D） distribution of H2O concentration and temperature in a simulated combustion flame.This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy.It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid,and after that point,the number of projection rays has little influence on reconstruction accuracy.It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method.In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed,and the capability of this new method is evaluated by using appropriate assessment parameters.By using this new approach,not only the concentration reconstruction accuracy is greatly improved,but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation.Finally,a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method.Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles.This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices.

3D Printing Hip Prostheses Offer Accurate Reconstruction,Stable Fixation,and Functional Recovery for Revision Total Hip Arthroplasty with Complex Acetabular Bone Defect

Complicated and large acetabular bone defects present the main challenges and difficulty in the revision of total hip arthroplasty(THA).This study aimed to explore the advantages of three-dimensional(3D)printing technology in the reconstruction of such acetabular bone defects.We retrospectively analyzed the prognosis of four severe bone defects around the acetabulum in three patients who were treated using 3D printing technology.Reconstruction of bone defect by conventional methods was difficult in these patients.In this endeavor,we used radiographic methods,related computer software such as Materialise's interactive medical image control system and Siemens NX software,and actual surgical experience to estimate defect volume,prosthesis stability,and installation accuracy,respectively.Moreover,a Harris hip score was obtained to evaluate limb function.It was found that bone defects could be adequately reconstructed using a 3D printing prosthesis,and its stability was reliable.The Harris hip score indicated a very good functional recovery in all three patients.In conclusion,3D printing technology had a good therapeutic effect on both complex and large bone defects in the revision of THA.It was able to achieve good curative effects in patients with large bone defects.

Niche Genetic Algorithm with Accurate Optimization Performance

Based on crowding mechanism, a novel niche genetic algorithm was proposed which can record evolution- ary direction dynamically during evolution. After evolution, the solutions’s precision can be greatly improved by means of the local searching along the recorded direction. Simulation shows that this algorithm can not only keep population diversity but also find accurate solutions. Although using this method has to take more time compared with the standard GA, it is really worth applying to some cases that have to meet a demand for high solution precision.

Occurrence and Epidemic Dynamics and Accurate Prevention and Control of Important Sugarcane Pests and Diseases in the Sugarcane Areas of Yunnan

Based on investigation and research, according to the current actual production of sugarcane, the occurrence dynamics and outbreak causes of important pests and diseases that seriously affect sugarcane production were summarized, and accurate and efficient green prevention and control technology was put forward according to the occurrence and damage characteristics of important pests and diseases, such as strengthening sugarcane introduction and quarantine, breeding and selecting varieties resistant to diseases and pests, promoting the use of detoxified healthy seedlings vigorously, applying lamp trapping technology on a large scale, scientifically guiding and promoting biological prevention and control technology, practically promoting the precise and efficient application of slow-release long- acting and low toxic pesticides, strengthening field management, spraying pesticides in time at the early stage of a disease, and doing a good job of monitoring and emergency prevention and control of sudden pests.

New finite strain elastoplastic equations for accurately and explicitly simulating pseudoelastic-to-plastic transition effects of shape memory alloys

A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions representing uniaxial loading and unloading curves,explicit multi-axial expressions for the three hardening quantities incorporated in the new model proposed are derived in unified forms for the purpose of automatically and accurately simulating complex pseudoelastic-to-plastic transition effects of shape memory alloys(SMAs)under multiple loading-unloading cycles.Numerical examples show that with only a single parameter of direct physical meaning for each cycle,accurate and explicit simulations may be achieved for extensive data from multiple cycle tests.

Dynamical Correction of Control Laws for Marine Ships’ Accurate Steering

The objective of this work is the analytical synthesis problem for marine vehicles autopilots design. Despite numerous known methods for a solution, the mentioned problem is very complicated due to the presence of an extensive population of certain dynamical conditions, requirements and restrictions, which must be satisfied by the appropriate choice of a steering control law. The aim of this paper is to simplify the procedure of the synthesis, providing accurate steering with desirable dynamics of the control system. The approach proposed here is based on the usage of a special unified multipurpose control law structure that allows decoupling a synthesis into simpler particular optimization problems. In particular, this structure includes a dynamical corrector to support the desirable features for the vehicle＇s motion under the action of sea wave disturbances. As a result, a specialized new method for the corrector design is proposed to provide an accurate steering or a trade-off between accurate steering and economical steering of the ship. This method guaranties a certain flexibility of the control law with respect to an actual environment of the sailing;its corresponding turning can be realized in real time onboard.

Accurate Fault Location Modeling for Parallel Transmission Lines Considering Mutual Effect

:A new accurate algorithms based on mathematical modeling of two parallel transmissions lines system(TPTLS)as influenced by the mutual effect to determine the fault location is discussed in this work.The distance relay measures the impedance to the fault location which is the positive-sequence.The principle of summation the positive-,negative-,and zero-sequence voltages which equal zero is used to determine the fault location on the TPTLS.Also,the impedance of the transmission line to the fault location is determined.These algorithms are applied to single-line-to-ground(SLG)and double-line-to-ground(DLG)faults.To detect the fault location along the transmission line,its impedance as seen by the distance relay is determined to indicate if the fault is within the relay’s reach area.TPTLS under study are fed from one-and both-ends.A schematic diagrams are obtained for the impedance relays to determine the fault location with high accuracy.

Research on Value Assessment-Based Accurate Identification of Government and Corporate Customers of Telecom Operators

Aiming at discovering target customers,this article establishes the value assessment system for government& corporate customers according to the level,stability and accessibility of customer value.With 137 customers as samples,it builds the government & corporate customer value assessment system through analytic hierarchy process(AHP) and identifies target government &corpora te customers by indicator optimization,model fitting and cluster analysis.All these achievements help accurate identification of high-value government and corporate customers and optimization of resource allocation for customer service.

Development of an accurate nursing program based on function in chronic venous leg ulcers:protocol for matching function status with nursing interventions using the Delphi survey

Objective: Venous leg ulceration(VLU) is one of the complications of lower extremity venous reflux and reflux disorder of severe diseases, with many adverse effects on patient’s work and life. Nowadays, more and more patients with VLU accept wound care in community setting. Clinical nurses generally take care of the patients based on their own experiences. Healing in VLU is an incredibly complex process, which puzzles even experts. The majority of general nurses do not have this level of expertise, especially those nurses serving in community. Function is the basis of nursing activities. Patients always show different clinical manifestations and selfcare abilities due to various function states, which cannot be reflected completely by the existing nursing practice. How to describe nursing practice standardized in order to demonstrate the effectiveness of interventions and facilitate interdisciplinary communication is another urgent problem. Therefore, the aim of this project is to develop an accurate nursing program based on function in chronic venous leg ulcers, which can both satisfy the needs of patients and promote nursing revolution.Methods: This study will use International Classification of Functioning Disability and Health as a framework to choose suitable functions and to filter function classification standards of chronic venous leg ulcers through evidence-based systematic research.Nursing interventions related to VLU are selected based on Nursing Interventions Classification, adding other nursing activities by methods of evidence-based systematic review and clinical observation. Then, nursing interventions and function status are matched through steering committee. Finally, the Delphi survey method is adopted to make nursing program native and scientific.Conclusions: This study is expected to be very significant and meaningful in using standardized nursing terminology. The nursing program established could better meet the needs of both patients with chronic venous leg ulcers and clinical nurses, promoting the development of wound specialist and standardized nursing language.

DNS analysis of incipient drop impact dynamics using an accurate level set method

A series of 2D direct numerical simulations were performed with an accurate level set method for single drop impacts.The adopted ACLS method was validated to be efficient with perfect mass conservation in both normal and oblique impacts.A square-root correction for neck bases was modified in accuracy as well as scope of applications.In addition,process of jet formation and evolution was studied to reveal internal dynamics in drop impacts.It's found that pressure gradient and vortex are coexisting and completive reasons for jet topology while the inclined angle has a significant effect on them.Mechanisms of jet formation and evolution are different in the front and back necks.With the help of PDF distribution and correction calculation,a compromise in the competition is observed.This work lays a solid foundation for further studies of dynamics in gas-liquid flows.

Real-time accurate hand path tracking and joint trajectory planning for industrial robots(Ⅰ)

Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which results in the heavier online computational burden for the robot controller. Aiming at overcoming this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method. Through selecting some extra knots on the specified hand path by a certain rule and introducing a sinusoidal function to the joint displacement equation of each segment, this method can greatly raise the path tracking accuracy of robot′s hand and does not change the number of the path′s segments. It also does not increase markedly the computational burden of robot controller. The result of simulation indicates that this method is very effective, and has important value in increasing the application of industrial robots.

Accurate Registration of Remote Sensing Images Based on Local Optimal Transformation

As the basic work of image stitching and object recognition,image registration played an important part in the image processing field.Much previous work in registration accuracy and realtime performance progressed very slowly,especially in registrating images with line feature.An innovative method for image registration based on lines is proposed,it can effectively improve the accuracy and real-time performance of image registration.The line feature can deal with some registration problems where point feature does not work.Our registration process is divided into two parts.The first part determines the rough registration transformation relation between reference image and test image.Then the similarity degree among different transformation and modified nonmaximum suppression(MNMS)algorithms are obtained,which produce local optimal solution to optimize the rough registration transformation.The final optimal registration relation can be obtained from two registration parts according to the match scores.The experimental results show that the proposed method makes a more accurate registration relation and performs better in real-time situation.

Accurate calculations of the high-pressure elastic constants based on the first-principles

The energy term corresponding to the first order of the strain in Taylor series expansion of the energy with respect to strain is always ignored when high-pressure elastic constants are calculated. Whether the modus operandi would affect the results of the high-pressure elastic constants is still unsolved. To clarify this query, we calculate the high-pressure elastic constants of tantalum and rhenium when the energy term mentioned above is considered and neglected, respectively.Results show that the neglect of the energy term corresponding to the first order of the strain indeed would influence the veracity of the high-pressure elastic constants, and this influence becomes larger with pressure increasing. Therefore, the energy term corresponding to the first-order of the strain should be considered when the high-pressure elastic constants are calculated.