汽车零件淬火技术模拟的动向

淬火技术,从齿轮的简单浸淬到复杂的压淬,在汽车制造业中的应用非常广泛。由于在制造过程中会发生复杂的物理现象,所以为了获得要求的性能,淬火工艺参数的选定也很复杂。近几十年来,已成功地采用计算机模拟来优化热处理工艺。本文列举了一些实例来阐述模拟技术的状况,包括淬火过程的物理现象,用于预测汽车零件热处理后的显微组织、力学性能和畸变的耦合模型的理论背景。

A Parallel Boundary Element Formulation for Tracking Multiple Particle Trajectories in Stoke’s Flow for Microfluidic Applications

A new formulation for tracking multiple particles in slow viscous flow for microfluidic applications is presented.The method employs the manipulation of the boundary element matrices so that finally a system of equations is obtained relating the rigid body velocities of the particle to the forces applied on the particle.The formulation is specially designed for particle trajectory tracking and involves successive matrix multiplications for which SMP(Symmetric multiprocessing)parallelisation is applied.It is observed that present formulation offers an efficient numerical model to be used for particle tracking and can easily be extended for multiphysics simulations in which several physics involved.

WEAK UNCORRELATEDNESS OF RANDOM VARIABLES

New measures of independence for n random variables, based on their moments, are studied. A scale of degrees of independence for random variables which starts With uncorrelatedness （for n = 2） and finishes at independence is constructed. The scale provides a countable linearly ordered set of measures of independence.

MEIR-KEELER TYPE CONTRACTIONS FOR TRIPLED FIXED POINTS

In 2011, Berinde and Borcut [6] introduced the notion of tripled fixed point in partially ordered metric spaces. In our paper, we give some new tripled fixed point theorems by using a generalization of Meir-Keeler contraction：

Determination of Watershed Boundaries in Turkey by GIS Based Hydrological River Basin Coding

A study was performed to develop hydrological river basin coding for Turkish river basins using the pfafstetter coding system. The coding system developed in this study is based on the combination of ECRINS and pfafstetter methods. River Basin District concepts were incorporated in this method so that it can be applicable to the management of Turkish River Basins. Developed hydrological river basin coding system is flexible, versatile and fits to all types of basins in Turkey. In order to show the efficiency of the coding system, it was applied to three river basins each of which has different hydrological and topographical features from the others. The basins used for the application of the coding system have complex features such as being transboundary basins, or being coastal basins whose discharge is not joining to the main drainage system, or being a closed basin discharging to an inland lake. Using the developed hydrological river basin coding defines river basin boundaries accurately, preventing conflicts in sectorial water allocation that are caused by uncertainty in the locations of water sources, producing a base for determining water potential and estimating extreme hydrological events of the basin, producing a basis for the prevention of water disputes among stakeholders within the basin, and helping implementation of Integrated Water Resources Management (IWRM) at basin level.

Transcarotid transcatheter aortic valve implantation with a novel balloon expandable Myval^(■) THV under the local anesthesia

Since it was first acquainted to us in 2002,tr-anscatheter aortic valve implantation(TAVI)was rapidly applied and earned worldwide approval.TAVI is the standard of care for patients with symptomatic severe aortic stenosis(AS),at in-termediate to high-risk and in some low-risk pa-tients in light of the recent data,principally if it can be performed transfemoral approach.

Epstein Barr Virus Infection Induced Suspected Acute Myocarditis in COVID-19 Pandemic

Background: Epstein Barr Virus infection (EBV) could be associated with cardiovascular disease, including myocarditis. We informed a case of EBV infection presenting initially as myocarditis, followed 5 days later by the typical symptoms of infectious mononucleosis. Case Presentation: A 19-year-old man with persistent retrosternal chest pain was admitted to the emergency department. On physical examination, the patient had sub-febrile fever (37.2°C) and palpable cervical lymphadenopathy, with no hepatosplenomegaly. Initial ECG has repolarization abnormalities in leads II, aVF and III. Laboratory testing revealed elevated cardiac enzymes and liver enzymes (high sensitive troponin I levels 3000 ng/mL, aspartate transaminase 158 U/L, alanine transaminase 100 U/L). Blood white cells were 10,500 μL, platelet level were low 98,000 (thrombocytopenia), and lenfo-monocytosis in complete blood count. We hospitalized the patients the intensive coronary unit (ICU) because of high troponin levels. We recognized hypokinesia of the posterolateral wall of the left ventricle with mild impaired systolic function and increased perimyocardial brightness by echocardiography. Antibody serology tests showed that the anti-EBV capsid antigen IgM (EBV-VCA) was positive, EBV-VCA) IgG was negative. Other etiologies were excluded. Therefore, the patient was referred to cardiac positron emission tomography due to technic problems of magnetic resonance imaging device. We documented in positron emission tomography imaging that increased 18F-FDG uptake on posterior and posterolateral walls of left ventricle (indicating a large jeopardized area). We diagnosed suspected diagnosis of myocarditis without associated pericarditis. We monitored the patient and gave beta blocker, and aldosterone antagonists. Complications in the intensive care unit not occurred. We discharged patients after one week. After three weeks, we re-evaluated the patient. We not observed wall segment motion abnormality on echocardiography and liver tests were near normal. Conclusion: In suspected EBV myocarditis, 18F-FDG PET-CT cardiac positron emission tomography imaging represents an interesting noninvasive imaging technique to identify inflammatory processes in acute myocarditis and can be considered in patients with contraindications/unavailable to cardiac magnetic resonance.

Performance Analysis of Techniques Used for Determining Land Mines

Today, remote sensing is used for different methods and different purposes. In all of the detection methods, some considerations such as low energy consumption, low cost, insensitivity to environmental changes, high accuracy, high reliability and robustness become important. Taking into account these facts, remote sensing methods are used in applications such as geological and archeological research, engineering areas, health services, preserving and controlling natural life, determination of underground sources, controlling air, sea and road traffic, military applications, etc. The method to be used is based on the object type to be detected, material to be made, and location to be found. The remote sensing methods from the past up to today can be listed as acoustic and seismic, ground penetration radar (GPR) detection, electromagnetic induction, infrared (IR) imaging, neutron quadrupole resonance (NQR), thermal neutron activation (TNA), neutron back scattering, X-ray back scattering, and magnetic anomaly detection. In these methods, detected raw images have to be processed, filtered and enhanced. In order to achieve these operations, some algorithms are needed to be developed. In this study, the methods used in detecting land mines remotely and their performance analysis have been given. In this way, the last situation on the advantages and disadvantages of methods used, application areas and detection accuracies are determined. Furthermore, the algorithms such as transmission line matrix (TLM), finite difference time-domain (FDTD), the method of moment (MoM), split step parabolic equation (SSPE) and image processing and intelligent algorithms are presented in detail.

Low temperature thermoluminescence behaviour of Y_2O_3 nanoparticles

Y_2O_3 nanoparticles were investigated using low temperature thermoluminescence (TL) experiments. TL glow curve recorded at constant heating rate of 0.4 K/s exhibits seven peaks around 19, 62, 91,115,162,196 and 215 K. Activation energies and characteristics of traps responsible for observed curves were revealed under the light of results of initial rise analyses and T_(max)-T_(stop) experimental methods. Analyses of TL curves obtained at different stopping temperatures resulted in presence of one quasi-continuously distributed trap with activation energies increasing from 18 to 24 meV and six single trapping centers at49, 117, 315, 409, 651 and 740 meV. Activation energies of all revealed centers were reported in the present paper. Structural characterization of Y_2O_3 nanoparticles was accomplished using X-ray diffraction and scanning electron microscopy measurements.

Synthesis and thermoluminescence properties of rare earth oxides (Y, Ce-Lu) doped lithium triborate

Lithium triborate （LiB3O5） was synthesized by high temperature solid-state reaction method, and then rare earth oxides were doped into LiB3O5 to enhance its thermoluminescent （TL） properties. The identification and characteristics of the obtained compounds were determined by X-ray diffraction （XRD）, Fourier transform infrared （FTIR） analyses, differential thermal analyses （DTA） and scanning electron microscopy （SEM）. The glow curves were obtained using a thermoluminescent （TL） reader. The results revealed that all the rare earth oxides were not good activators for lithium triborate and the obtained compounds could not be used for dosimetric applications.

Norming Subspaces Isomorphic to l_1

Norming subspaces are studied widely in the duality theory of Banach spaces. These subspaces are applied to the Borel and Baire classifications of the inverse operators. The main result of this article asserts that the dual of a Banach space X contains a norming subspace isomorphic to l1 provided that the following two conditions are satisfied： （1） X＊ contains a subspace isomorphic to l1; and （2） X＊ contains a separable norming subspace.

Kinases and glutathione transferases:selective and sensitive targeting

Kinases,representing almost 500 proteins in the human genome,are responsible for catalyzing the phosphorylation reaction of amino acid residues at their targets.As the largest family of kinases,the protein tyrosine kinases(PTKs)have roles in controlling the essential cellular activities,and their deregulation is generally related to pathologic conditions.The recent efforts on identifying their signal transducer or mediator role in cellular signaling revealed the interaction of PTKs with numerous enzymes of different classes,such as Ser/Thr kinases(STKs),glutathione transferases(GSTs),and receptor tyrosine kinases(RTKs).In either regulation or enhancing the signaling,PTKs are determined in close interaction with these enzymes,under specific cellular conditions,such as oxidative stress and inflammation.In this concept,intensive research on thiol metabolizing enzymes recently showed their involvement in the physiologic functions in cellular signaling besides their well known traditional role in antioxidant defense.The shared signaling components between PTK and GST family enzymes will be discussed in depth in this research review to evaluate the results of recent studies important in drug targeting for therapeutic intervention,such as cell viability,migration,differentiation and proliferation.

Properties of the P_(c)(4312)pentaquark and its bottom partner

We present an analysis of the newly observed pentaquark P(4312)+to shed light on its quantum num-bers.To do that,the QCD sum rules approach is used.The measured mass of this particle is close to the∑++cD-threshold and has a small width,which supports the possibility of its being a molecular state.We consider an inter-polating current in a molecular form and analyze both the positive and negative parity states with spin-1/2.We also consider the bottom counterpart of the state with similar molecular form.Our mass result for the charm pentaquark state supports that the quantum numbers of the observed state are consistent with J^(P)=1/2^(-).

能寻找蜂鸣器共振频率的压电驱动器

压电蜂鸣器作为音频信号发生器有着广泛的用途．因为它们功耗低，声音清晰而有穿透力。蜂鸣器的外部驱动电路或自驱动电路要求振荡于压电元件的共振频率。压电元件在其共振频率处提供最大的声压输出。但是．一只压电元件的共振频率有最大±15％的公差。因此．调谐到标称频率的外部驱动电路很可能失去实际的谐振点。本设计是一个压电元件的外部驱动电路，它会自动找到实际的谐振频率。