Design,analysis and experimental investigations of a high precision flexure-based microgripper for micro/nano manipulation

In this paper, a flexure-based piezoelectric actuated microgripper is presented for high precision micro/nano manipulation tasks. A new design of microgripper based on a three-stage displacement amplification mechanism is utilized to magnify the piezoelectric actuator displacement. A bridge-type mechanism with a two-sided output port is serially connected with two consecutive lever mechanisms. The output motion on both sides is linearized by parallelogram mechanisms. The single-notch and double-notch circular flexural hinges were used in lever, bridge-type and parallelogram configuration. The displacement amplification and transmission mechanisms are arranged symmetrically to obtain stability of shape and compact layout of the entire microgripper. Analytical modeling was performed to establish an input and output displacement relationship. Finite Element Analysis (FEA) method was utilized to evaluate the performance of the microgripper. The design parameters of the microgripper were optimized through FEA method. The simulation results of the FEA method were validated through experimentation on the established design. The experimental results show that the total displacement amplification ratio of the microgripper is 12.76. The microgripper jaws have a high precision positioning accuracy. The microgripper also achieves a high-level working mode frequency of 1044 Hz, which is capable of accommodating rapid transient responses.     

From "macro" to "micro" manipulation: models and experiments

This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed.     

T-BLAST for wireless communications: first experimental results

In earlier papers , we described a novel multitransmit, multireceive (MTMR) antenna system for wireless communications. This new system, turbo Bell-Labs layered space-time (T-BLAST) architecture, combines the benefits of layered space-time coding concepts and turbo principles in the multitransmit, multireceive antenna system design. In particular, the random layered space-time codes designed by using a set of block convolutional codes and random space-time interleavers and the space-time turbo-like decoding operation allow T-BLAST to realize the benefits of MTMR systems in a computationally feasible manner. The goal of this paper is to present experimental results of T-BLAST based on real-life data collected using the Bell-Labs experimental multiple antenna system with eight transmit and five and six receive antennas. The experimental results show the practical virtues of T-BLAST.     

Optimum feed for large radio-telescopes: experimental results

Corrugated waveguide structures can be used to design highly efficient aperture-type feeds for both spherical and paraboloidal reflector antennas. The letter presents a brief account of experimental results obtained with a 2-hybrid-mode horn. It is shown that theoretical and experimental results agree closely.     

Design and dynamics of a 3-DOF flexure-based parallel mechanism for micro/nano manipulation

This paper presents the mechanical design and dynamics of a 3-DOF (degree of freedom) flexure-based parallel mechanism. Flexure hinges are used as the revolute joints to provide smooth and high accurate motion with nanometer level resolution. Three piezoelectric actuators are utilized to drive active links of the flexure-based mechanism. The inverse dynamics of the proposed mechanism is established by simplifying flexure hinges into ideal revolute joints with constant torsional stiffnesses. Finite element analysis is used to validate the performance of the proposed 3-DOF flexure-based parallel mechanism. The interaction between the actuators and the flexure-based mechanism is extensively investigated based on the established model. Experiments are carried out to verify the dynamic performance of the 3-DOF flexure-based mechanism.     

针对低空微小型无人机的轻量型YOLOv5检测算法

针对低空微小型无人机对公共安全造成威胁的问题,本文基于YOLOv5(you only look once v5)网络提出了一种适用于移动端的轻量型目标检测模型YOLOv5＿SS。该模型以轻量型网络ShuffleNetv2替换YOLOv5原有的主干网络,引入SENet (squeeze-and-excitation networks)注意力机制,并采用Soft-NMS(soft non-maximum suppression)算法提升对密集重叠目标的检测效果。实验结果表明,该模型在数据集上对低空微小无人机进行检测的平均精确率均值(mean average precision@0.5,mAP₅₀)为92.75%,精度为90.49%,参数量为0.237 4 M,浮点运算数为0.9千兆浮点运算(giga floating-point operations, GFLOPS)。具有检测精度高、内存占用率低的特点,有利于在移动终端上部署且在复杂背景及密集目标的场景下均有较好的检测效果。     

Area-based results for mine detection

The cost and the closely related length of time spent in searching for mines or unexploded ordnance (UXO) may well be largely determined by the number of false alarms. False alarms can result in time consuming digging of soil or in additional multisensory tests in the minefield. The authors consider two area-based methods for reducing false alarms. These are: (a) the previously known “declaration” technique and (b) the new δ technique, which they introduce. They first derive expressions and lower bounds for false-alarm probabilities as a function of declaration area and discuss their impact on receiver operation characteristic (ROC) curves. Second, they exploit characteristics of the statistical distribution of sensory energy in the immediate neighborhood of targets and of false alarms from available calibrated data, to propose the δ technique, which significantly improves discrimination between targets and false alarms. The results are abundantly illustrated with statistical data and ROC curves using electromagnetic-induction sensor data made available through DARPA from measurements at various calibrated sites     

Buffer and bandwidth allocation for TCP data traffic: experimental results

This paper discusses the dimensioning of buffers and the bandwidth allocation for data traffic in the ATM network. Data traffic is notoriously complex and bursty, making such dimensioning a difficult task. However, the COMBINE project, when dimensioning their InterWorking Units (IWUs), adopted a Poissonian packet arrival model, based upon the argument that burstiness at timescales higher than that of a packet arrival are a problem to be tackled by flow control at higher layers. This paper presents experimental results from the COMBINE testbed that show that this hypothesis was justified and that good TCP goodput was obtained based upon this dimensioning approach, due to TCP's ability to adapt to network congestion. However, it is also shown that it was the TCP algorithm that was ultimately responsible for controlling the packet loss ratio in the network and not the bandwidth allocation or buffer size. The results highlight the importance of taking into account the mutual influence between the ATM layer and the transport layer congestion control algorithms.     

Time-coded aperture tomography: experimental results

In this paper, we discuss the applicability of a time-coded aperture system especially designed for thyroid tomography on the basis of phantom experiments. Our studies show that 1) the quality of the reconstructions is high (e.g., a cold spot of 6 mm diameter in a thyroid phantom can easily be detected), and 2) the reconstruction can be carried out in less than 11 min on a standard 16 bit minicomputer (HP1000). It is therefore concluded that the clinical potentiality of the device is good.     

HRDA-Net:面向真实场景的图像多篡改检测与定位算法

针对主流篡改数据集单幅图像仅包含一类篡改操作,且对真实图像定位存在"伪影"问题,构建面向真实场景的多篡改数据集(MM Dataset),每幅篡改图像包含拼接和移除2种篡改操作.针对多篡改检测与定位任务,提出端到端的高分辨率扩张卷积注意力网络(HRDA-Net),利用自顶向下扩张卷积注意力(TDDCA)模块融合图像RGB...     

Improvements in W-CDMA: principles and experimental results

This article first reviews the channel structure and spreading code assignment for the physical layer and transport channel multiplexing along with a sophisticated rate-matching scheme that accommodates composite transport channels with various levels of quality of service (QoS) on one physical channel. Then, the key technologies of wideband ds-cdma (w-cdma) wireless access are presented and the results of experiments pertaining to these technologies are evaluated. Flexible system deployment is possible by employing inter-cell asynchronous operation with a three-step fast cell search method. The signal-to-interference power ratio (sir) measurement based fast transmit power control (tpc) guarantees the minimum transmit power according to the channel load and the changes in the link conditions due to fading. Furthermore, various diversity technologies are described such as pilot symbol-assisted (psa) coherent Rake combining, antenna diversity, site diversity (soft/softer handover), and transmit diversity in the forward link that are effective in decreasing the required transmit power, which results in increases system capacity. This article also presents link-capacity enhancing techniques such as using an interference canceller (IC) and adaptive antenna array diversity (AMD) receiver/transmitter. Experimental results are presented for an actual multipath fading channel that indicate the potential of the IC and aaad transceiver to decrease the mobile transmit power in the reverse link and interference from high rate users with high transmit power in the forward link.     

All-digital 1-bit RSFQ autocorrelator for radioastronomyapplications: design and experimental results

We present the design of a rapid single-flux-quantum all-digital 1-bit autocorrelator for submillimeter spectrometry applications, featuring 4-GHz input signal bandwidth, double oversampling quantizer, and 16-Mb/s-per-channel output rate. The correlator consists of a digital delay line with multiplication and an array of accumulators with parallel readout. We report experimental results for a three-stage delay line (294 Josephson junctions) and a 4×4 array of accumulators (288 Josephson junctions) fabricated in HYPRES' standard 3.5-μm 1000-A/cm² Nb-trilayer process     

中国移动恶意代码检测与治理方案

本文通过分析流行的恶意代码特征,结合中国移动恶意代码治理现状,提出中国移动进行恶意代码检测与治理新趋势。     

Useful experimental results for Earth-satellite rain attenuation modeling

Results pertaining to vertical profiles of rain rates derived from radar data as well as normalized cumulative probabilities of rain rates, which may be applicable over large areas of the world, are presented. We believe these results to be useful in the areas of earth-satellite rain attenuation modeling and prediction at frequencies above 10 GHz.     

A broad-band resistively loaded V-antenna: experimental results

A broadband receiving antenna was realized using a resistively loaded thin-film V-monopole and a 500-Ω oscilloscope probe. The pulse-receiving performance of the antenna was evaluated in a time-domain antenna range, for various directions of the incident pulse. The antenna is capable of receiving a 520 ps electromagnetic pulse, incident within 45° from the boresite direction, with good fidelity. The antenna was also tested in a transverse electromagnetic cell in the time and frequency domains. The frequency-domain receiving transfer function of the antenna was found to be within -57±3 dB in the 22 MHZ to 1.1 GHz frequency range     

高密度LED焊点微空洞的X射线检测和分析

利用高精度X射线检测设备分别对用Sn37Pb焊膏和Sn3.0Ag0.5Cu焊膏组装的高密度LED灯板进行焊后和老化后的微空洞检测,观察了焊点的微空洞缺陷,并计算微空洞尺寸。结果表明:老化前微空洞面积与焊点面积比在10%~25%的,Sn3.0Ag0.5Cu焊点中约含25.5%,略大于Sn37Pb焊点的23.5%,且明显小于Sn3.0Ag0.5Cu焊点老化后的31.4%。两种焊点老化前后微空洞所占面积比都在<25%的合格范围内,但Sn3.0Ag0.5Cu焊点更易形成微空洞。     

Low-voltage CMOS current-mode preamplifier: analysis and design

This paper presents the analysis and design of a new low-voltage fully balanced differential CMOS current-mode preamplifier for multi-Gbps series data communications. The minimum supply voltage of the proposed preamplifier is V/sub T/+V/sub sat/. The preamplifier employs a balanced configuration to achieve large bandwidth and to minimize the effect of bias-dependent mismatches. Two new bandwidth enhancement techniques, namely inductive series peaking and current feedback that are specific to low-voltage CMOS current-mode circuits, are introduced. The inductive series peaking technique utilizes the resonant characteristics of LC networks to achieve both a flat frequency response and maximum bandwidth. Current feedback extends bandwidth, lowers input impedance, and improves dynamic range. The employment of both techniques further increases the bandwidth, reduces the value of the series peaking inductor, and improves noise performance of the pre-amplifier at high frequencies. The preamplifier has been designed using a 0.18-/spl mu/m 6-metal 1-poly 1.8-V CMOS technology. Simulation results from Spectre with BSIM3.3 device models that account for device parasitics demonstrate that the preamplifier has a flat frequency response with 25.3 dB dc current gain or equivalently 60 dB/spl Omega/ transimpedance gain with a 50-/spl Omega/ load and bandwidth of 2.15 GHz.     

Polyelectrolytes-coated gold nanoparticles detection by PEDOT:PSS electrochemical transistors

Electrochemical transistors made of PEDOT:PSS are used to detect different polymeric shells used to functionalize the nanoparticles for drug delivering. The devices were realized drawing their configuration directly on glass with a micro-syringe and micro-positioning system. This permits a great flexibility in the definition of the needed geometry giving the possibility to maximize the signal to the different polymeric shells. The realized devices exhibit different responses respect to the functionalized nanoparticles and in particular respect to the polymer used for their functionalization. The linear behavior observed gives the possibility to use these devices to detect the quantity of polymer loaded on the nanoparticles. This opens to the possibility to determine the quantity of drugs that could be loaded inside the functionalized shells and also to detect the kinetics of drug delivery or, even, to monitor the stability of the nanoparticles themselves.     

Geometrical effect of bump resistance for flip-chip solder joints: Finite-element modeling and experimental results

The bump resistance of flip-chip solder joints was measured experimentally and analyzed by the finite-element method. Kelvin structures for flip-chip solder joints were designed and fabricated to measure the bump resistance. The measured value was only about 0.9 mΘ at room temperature, which was much lower than that expected. Three-dimensional (3-D) modeling was performed to examine the current and voltage distribution in the joint. The simulated value was 7.7 mΘ, which was about 9 times larger than the experimental value. The current crowding effect was found to be responsible for the difference in bump resistance. Therefore, the measured bump resistance strongly depended on the layout of the Kelvin structure. Various layouts were simulated to investigate the geometrical effect of bump resistance, and a significant geometrical effect was found. A proper layout was proposed to measure the bump resistance correctly. The Kelvin structure would play an important role in monitoring void formation and microstructure changes during the electromigration of flip-chip solder joints.     

Some experimental results for a capacitively loaded V antenna

A V antenna with lumped capacitive loading is investigated experimentally. The loading is in the form of narrow transversal gaps along the antenna, which are progressively closer together towards the antenna ends. The antenna is found to exhibit remarkable broadband properties in admittance, and to have a more directive radiation pattern than a straight dipole with approximately similar loading.