Analyzing and exemplify the phenomenon of lossing control in vibration experiment

With science and technology development,vibration testing as the most important item in reliability test is becoming more and more important,at the same time,vibrate condition becoming more and more complicated,the phenomenon increases that the output of controller goes beyond controlling range so that destroy the specimen. In this paper,some skills such as how to set the parameters of force controller,where to place the sensor,which material to be chosen and which skills to be used while making jigs were introduced to avoid the just matter. At last,some examples were given to prove the validity of the method proposed.

双官能团界面改性剂对WPC综合性能的影响

采用新型双官能团偶联剂对木粉进行表面处理,并通过单因素法研究偶联剂种类和含量对材料综合性能的影响,并结合扫描电镜进行了微观形貌分析。结果表明:新型双官能团偶联剂有优于传统偶联剂的改性效果。当添加量为0.8%时,木粉与PVC树脂相容性达到较理想状态,抗弯强度、抗弯弹性模量、冲击韧性和拉伸强度达到最佳值,分别为35.76MPa,2 378.32MPa,1 5.08kJ/m^2,14.01MPa。

Preliminary experimental study on applicability of Lorentz force velocimetry in an external magnetic field

Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field(ExMF). Two types of Ex MFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet(PM) and another generated by an electromagnet(EM) on the order of 2 T. Two forces, including the magnetostatic force between the Ex MF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition,Ex MFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate Ex MF. However, the magnetostatic force will account for a high proportion of the measured force,thus inhibiting the normal LFV operation, if the Ex MF is too high.

Schottky forward current transport mechanisms in AlGaN/GaN HEMTs over a wide temperature range

The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated by temperature-dependent current-voltage （T-I-V） measurements from 300 K to 473 K. The ideality factor and barrier height determined based on the thermionic emission （TE） theory are found to be strong functions of temperature, while present a great deviation from the theoretical value, which can be expounded by the barrier height inhomogeneities. In order to determine the forward current transport mechanisms, the experimental data are analyzed using numerical fitting method, considering the temperature-dependent series resistance. It is observed that the current flow at room temperature can be attributed to the tunneling mechanism, while thermionic emission current gains a growing proportion with an increase in temperature. Finally, the effective barrier height is derived based on the extracted thermionic emission component, and an evaluation of the density of dislocations is made from the I-V characteristics, giving a value of 1.49 × 10^7 cm^-2.

Nonlinear vibration of iced cable under wind excitation using three-degree-of-freedom model

High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force.In this paper,the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated.Considering the excitation caused by pulsed wind and the movement of the support,the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton's principle.By the Galerkin method,the partial differential equations are then discretized into ordinary differential equations.The method of multiple scales is then used to obtain the averaged equations of the iced cable,and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered.The numerical simulations are performed to investigate the dynamic response of the iced cable.It is found that there exist periodic,multi-periodic,and chaotic motions of the iced cable subjected to wind excitation.

An Advanced Quantum-Resistant Signature Scheme for Cloud Based on Eisenstein Ring

Signature,widely used in cloud environment,describes the work as readily identifying its creator.The existing signature schemes in the literature mostly rely on the Hardness assumption which can be easily solved by quantum algorithm.In this paper,we proposed an advanced quantum-resistant signature scheme for Cloud based on Eisenstein Ring(ETRUS)which ensures our signature scheme proceed in a lattice with higher density.We proved that ETRUS highly improve the performance of traditional lattice signature schemes.Moreover,the Norm of polynomials decreases significantly in ETRUS which can effectively reduce the amount of polynomials convolution calculation.Furthermore,storage complexity of ETRUS is smaller than classical ones.Finally,according to all convolution of ETRUS enjoy lower degree polynomials,our scheme appropriately accelerate 56.37%speed without reducing its security level.

Multiple Parameters Side Channel Signal Analysis Using in Hardware Trojan Detection

As the process of economic globalization deepens,a large variety of integrated circuit designers tends to move the chip's manufacturing to the developing country.But during the globalization of semiconductor design and fabrication process,integrated circuits are suffering from increasing malicious alterations from the untrusted foundries,which pose a serious threat to the military,finance,transportation and other critical systems.An noninvasive approach was presented to measure the physical "sidechannel"parameter of a chip such as current or delay,which is effectively capable of detecting the malicious hardware alternations.The intrinsic relationship of a circuit's side-channel parameters was exploited to distinguish the effect of a Trojan in the presence of large random noise and process noise,such as the Dynamic current(IDDT)versus the maximum operating frequency(Fmax)correlation.The Monte Carlo analysis in Hspice using ± 20% Gauss variations in transistor threshold voltage(Vth)was carried out to simulate the circuit state in the real world.Simulation Results show that this approach is effective to detect the ultra-small Trojans.

Low-temperature synthesis of sea urchin-like Co-Ni oxide on graphene oxide for supercapacitor electrodes

Transition metal oxides are ideal electrode materials used for supercapacitors.However,the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption.Herein,we report the synthesis of sea urchin-like Co3 O4-NiO composites supported on graphene oxide(GO) using a hydrothermal method followed by calcination with a low temperature(250℃).The obtained Co3O4-NiO/GO composite demonstrates a high specific capacitance of 883 F g^-1 at 1 A g^-1.Furthermore,upon coupling with an activated carbon(AC) positive electrode,an asymmetric cell of Co3 O4-NiO/GO//AC exhibits outstanding stability reflected by the high capacitance retention of 82% at a high current density of 10 A g^-1.The excellent electrochemical properties of the composite may be attributed to the good synergistic effect of Co3O4 and NiO,as well as the assembly of Co3 O4 and NiO into a sea urchin structure,which results in increased electron conductivity and more exposed electroactive sites leading to the promotion of the Faradaic redox process.

Domain decomposition based on the spectral element method for frequency-domain computational elastodynamics

We propose a domain decomposition method based on the spectral element method(DDM-SEM)for elastic wave computation in frequency domain.It combines the high accuracy of the spectral element method and the high degree of parallelism of a domain decomposition technique,which makes this method suitable for accurate and efficient simulations of large scale problems in elastodynamics.In the DDM-SEM,the original large-scale problem is divided into a number of well designed subdomains.We use the spectral element method independently for each subdomain,and the neighboring subdomains are connected by a frequency-domain version of Riemann transmission condition(RTC)for elastic waves.For the proposed method,we can employ the non-conforming meshes and different interpolation orders in different subdomains to maximize the efficiency.By separating the internal and boundary unknowns of each subdomain,an efficient and naturally parallelizable block LDU direct solver is developed to solve the final system matrix.Numerical experiments verify its accuracy and efficiency,and show that the proposed DDM-SEM can be a promising numerical tool for accurately and effectively solving large and multi-scale problems of elastic waves.It is potentially valuable for the frequency domain seismic inversion where multiple source illuminations are required.