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The 7-hole probe measurement system is mainly used to measure three-dimensional flow fields. During the measurement, the probe head was in direct contact with the measured object, and the head structure had a significant influence on the accuracy of the flow field measurement. The main influencing factors were the hole opening mode, hole position, and hole diameter. For a hemispherical 7-hole probe with perpendicular and forward-facing holes, orthogonal experiments with three levels and three factors (inflow velocity, hole position, and hole diameter) were designed, and additional experiments were conducted on the significant factors. The importance of factors was evaluated based on the correlation between different structural parameters and the pressure coefficient. The experiment was simulated using FLUENT, and the numerical simulation results demonstrated that the square of deviance at the inlet velocity, hole diameter, and hole position was 0.0018, 0.0013, and 0.3611, respectively. The position of the hole has a significant influence on the measurement results, but the influence of the inflow velocity and hole diameter is negligible, and the pressure coefficient is the smallest when the hole is at 45°. For the hemispherical 7-hole probe with forward facing hole, the hole is the best at approximately 45°, and considering the convenience of processing, the diameter of the hole can be selected as the diameter of the 1/10 probe.

Aiming at object grasping of indoor mobile robots, this paper develops an object localization system based on the fusion of a monocular camera and a two-axis-controlled laser ranging sensor. The system can locate the specified object in space without obtaining the background depth information of the object, which reduces the consumption of computational resources and has a low cost. According to the coordinate mapping of the object in the image, the measurement point of the laser ranging sensor is controlled to coincide with the target point by two servo motors in perpendicular axes. Thus, the spatial location of the target point can be determined from the rotation angles of the cradle head motors and the laser-measured distance together. To accurately control the rotation angles, a compound strategy combining feedback and feedforward is proposed. On the one hand, the feedback of the laser measurement point is introduced in the image coordinate to realize the close-loop control of the measurement point. On the other hand, a feedforward compensator based on disturbance observation is designed to reduce the influence of robot motion. An experimental setup is developed and substantial experiments are implemented to evaluate the performance of the proposed system. The results show that object localization can be effectively achieved with good accuracy and dynamic response.

Nasopharyngeal carcinoma (NPC) is a highly invasive and metastatic disease occurring in the nasopharynx. For early diagnosis or treatment, it is helpful to separate invasive nasopharyngeal carcinoma (NPC43) cells from epithelial (NP460) cells. However, the lack of proper in vivo models significantly hinders the systematic study of NPC. In this study, an in vitro two-layer scaffold platform was developed to mimic the extracellular matrix of the tissue that allows the investigation of carcinoma and epithelial cell migration behaviors. Three precisely controlled factors were designed to investigate how topographic cues affected migration of NP460 and NPC43 cells: overlay angles between the top and bottom layers, top layer thicknesses, and surface topography of the bottom layer ridges. These designs offered different surface contact areas for cells to probe and form focal adhesions as they migrated on the platforms. As NP460 and NPC43 cells respond differently to the surrounding microenvironments, when the top layers were perpendicular to the bottom layers, 66.3% NPC43 cells could move into the $10~\mu \text{m}$ wide trenches compared to 5.5% for NP460 cells. However, NP460 and NPC43 cells migrating into top layer trenches were hindered when the top layer was too shallow or too thick. Moreover, the gratings added on the bottom layer ridges promoted cells to squeeze into the trenches. These results yielded over 92.3% separation efficiency on platforms with a 15- $\mu \text{m}$ thick top layer being perpendicular to the bottom layer and gratings on the bottom layer ridges.

Various methods for automatic building extraction from remote sensing data including light detection and ranging (LiDAR) data have been proposed over the last two decades but a standard metric for evaluation of the extracted building boundary has not been found yet. An extracted building boundary from LiDAR data usually has a zigzag pattern with missing detail, which makes it hard to compare the boundary with its reference. The existing metrics do not consider the significant point (e.g., corner) correspondences, therefore, cannot identify individual extralap and underlap areas in the extracted boundary. This article proposes an evaluation metric for the extracted boundary based on a newly proposed robust corner correspondence algorithm that finds one-to-one true corner correspondences between the reference and extracted boundaries. Assuming a building has a rectilinear shape, corners and lines are first detected for the extracted boundary. Then, corner correspondences are obtained between the extracted and reference boundaries. Each corner has two corresponding lines on its two sides that ideally are perpendicular to each other. The corner correspondences are finally ranked based on their distance, angle, and parallelism of corresponding lines. The metric is defined as the average minimum distance $d_{\mathrm{avg}}$ from the extracted boundary points to their corresponding reference lines. Extralap and underlap areas are identified by comparing the point distances with $d_{\mathrm{avg}}$ . In experiments, the proposed metric performs more realistic than the existing metrics and finds the individual extralap and underlap areas effectively.

This paper presents a metasurface-based single-layer low-profile circularly polarized (CP) antenna with the wideband operation and its multiple-input multiple-output (MIMO) configuration for fifth-generation (5G) communication systems. The antenna consists of a truncated corner patch and a metasurface (MS) of a 2 × 2 periodic square metallic plates. The distinguishing feature of this design is that all the radiating elements (radiator and MS) are printed on the single-layer of the dielectric substrate, which ensures the low-profile and low-cost features of the antenna while maintaining high gain and wideband characteristics. The wideband CP radiations are realized by exploiting surface-waves along the MS and its radiation mechanism is explained in detail. The single-layer antenna geometry has an overall compact size of 1.0λ0 × 1.0λ0 × 0.04λ0. Simulated and measured results show that the single-layer metasurface antenna has a wide 10 dB impedance bandwidth of 23.4 % (24.5 - 31 GHz) (23.4 %) and overlapping 3-dB axial ratio bandwidth of 16.8 % (25 - 29.6 GHz). The antenna also offers stable radiation patterns with a high radiation efficiency (>95%) and a flat gain of 11 dBic. Moreover, a 4-port (2 × 2) MIMO antenna is designed using the proposed design by placing each element perpendicular to each other. Without a dedicated decoupling structure, the MIMO antenna shows an excellent diversity performance in terms of isolation between antenna elements, envelope correlation coefficient, and channel capacity loss. Most importantly, the operational bandwidth of the antenna covers the millimeter-wave (mm-wave) band (25 - 29.5 GHz) assigned for 5G communication. These features of the proposed antenna system make it a suitable candidate for 5G smart devices and sensors.

This paper proposes a multifocal lens design method named phase superposition method (PSM) and a methodology to increase the efficiency of metallic binary zone plates through a sub-wavelength slit array. The phase superposition method calculates the intensity at each focus, assuming a perfectly phase-matched modulation based on input light, and the size of the lens. Subsequently, based on the calculated focus intensity, the phases linearly related to the target intensity at each focus are combined. The sub-wavelength slit-assisted metallic binary plate assumes the sub-wavelength slit array as a dielectric in the light polarized perpendicular to the slit. It then controls the condition of the slit to invert the phase difference between the opened region and the slit region. By applying these methods, the trifocal lens was designed to verify our idea. The light was focused on three target positions. After applying the sub-wavelength slit structure, the amplitude was increased up to 90.11%, and the efficiency increase was 303.99% compared to that of a binary plate without the sub-wavelength slit.

Magnetic gears employ magnetic fields, rather than teeth, to perform the gearing action. At large gear ratios, cycloidal magnetic gears (CyMGs) can achieve higher torque densities than the more common coaxial magnetic gears. This paper compares CyMG topologies with consequent pole (CP) rotors against CyMGs with more conventional surface permanent magnet (SPM) rotors. CyMGs with CP rotors require less PM pieces than CyMGs with SPM rotors, which may simplify manufacturing. Each topology is optimized using a genetic algorithm with 2D finite element analysis (FEA). The simulation results demonstrate that CyMGs with CP rotors achieve lower VTD values than CyMGs with SPM rotors. However, if using a CP inner rotor eliminates the need for a PM retention sleeve and enables the use of a smaller effective air gap, CyMGs with CP rotors can achieve higher PM STs at high gear ratios than CyMGs with SPM rotors. CyMGs with CP rotors generally experience similar perpendicular magnetic forces and slightly higher eccentric magnetic forces, relative to CyMGs with SPM rotors. The optimal 2D designs are further investigated using 3D FEA, and, within this design set, the CyMGs with CP rotors experience more significant end effects than the CyMGs with SPM rotors.

We demonstrated atomic diffusion bonding (ADB) of wafers using AlN films at room temperature. Results showed that crystal lattice rearrangement occurred at the bonded interface and integrated AlN film with c-axis perpendicular to the film plane formed.

Field-free switching of perpendicular spin-orbit torque magnetic tunnel junction (p-SOT-MTJ) is investigated using micromagnetic simulation to evaluate the SOT critical current density (J$_{C, SOT}$). The spin-transfer torque (STT) can break the symmetry and ensure the deterministic switching of p-SOTMTJ without the external magnetic field. The decreasing SOT pulse width (t SOT ) below 1 ns causes the significant increase of J$_{C,SOT}$. The increasing STT current density (J STT ) can overcome the damping torque and reduce the J$_{C,SOT}$. For a short t SOT of 0.2 ns, the increase of STT current density (J STT ) from 0.64 MA/cm2 to 0.97 MA/cm$^{2}(V_{STT}$ from 0.2 V to 0.3 V) reduces the J$_{C,SOT}$ by 36%. As the spin Hall angle $(\theta_{SH})$ of SOT channels increases from 0.28 to 0.5, the J$_{C, SOT}$ can further be reduced by 46%.

In a photo-voltaic solar energy system, solar tracking can harness more energy compared to a fixed system. This paper presents a design of a Manual/Automatic Hybrid Dual Axis Solar Tracking System that tracks the sun's daily and seasonal motions. The hybrid tracker tries to ensure that the solar panel is always positioned perpendicular to the solar incident radiation by operating the tracker along two axes, of east to west (daily motion) and north to south (seasonal motion). The automatic tracking includes Time based Chronological Tracking and Light Dependent Resistor (LDR) based Active Tracking. Daily tracking is operated by a stepper motor while seasonal tracking is done manually by a gear system once a month. Results of the study show that the proposed hybrid dual-axis solar tracking system is capable of improving the overall energy efficiency by around 35%, over a fixed installation, in an economical manner.

The classical Ramo-Shockley theorem (RS) [1] , [2] gives the current induced on perfect conductors by the motion of nearby charges. It is a foundational result in vacuum electronics, discharge physics, and semiconductor devices. The original theorem was derived by assuming quasi-static fields, ignoring both relativistic and radiative effects. This paper illustrates, for the first time, how relativistic and electromagnetic effects modify RS in some simple examples and examines the magnitude of the corrections. Specifically, we present explicit, closed form analytic solutions of Maxwell’s equations for the induced current distribution on perfectly conducting plates due to the motion of a line charge moving either parallel or perpendicular to the plates. Our exact closed form solutions have been verified by several methods, including particle-in-cell simulations. Several novel features were revealed that are absent in the classical RS: electromagnetic transients due to the sudden acceleration of charge, multiple reflections of electromagnetic waves by conductors, and generation of an electromagnetic shock when the charge strikes a conductor and is subsequently removed. We have found that the classical RS works rather well otherwise, even for a highly relativistic beam, except near the wavefront(s) where the transients dominate. This partially explains the mystery as to why the non-relativistic RS has been very successful in the theory and numerical simulations of vacuum electronic devices, in which only the quasi-static, sinusoidal steady solutions are included. The electromagnetic shock could be a source of contamination on the quality of signals in satellite communication, by the electrons in a multipactor discharge [3] . These issues are being examined. The induced current due to motion of a point charge is also under investigation.

Acoustoelasticity (AE) aims at measuring the elastic nonlinearity of a medium based on the evolution of its shear wave speed as the medium is uniaxially stressed. In the field of biomedical imaging, AE was first applied on isotropic tissues such as breast and was recently adapted for transversely isotropic (TI) tissues such as muscles. However, the consideration of the TI geometry complexifies the AE equations, by adding supplementary NL terms (and NL elastic moduli) as well as by requiring the consideration of one more direction: the principal axis of the TI medium. Up to now, the development of AE in TI quasi-incompressible medium covers the nine simplest configurations where the principal axis of the TI medium, stress, polarization and propagation directions of the shear waves are either parallel or perpendicular one to the other. These requirements are difficult to meet experimentally and can lead to experimental biases. Therefore, the goal of the present work is to consider the angle dependency of the polarization and propagation directions with respect to the principal axis. Shear horizontal (SH) mode waves were considered and AE equations relating the speed of such waves to the applied stress as well as to the propagation angle with respect to the principal direction of the TI medium were retrieved. These relations were then experimentally validated on a TI Polyvinyl alcohol phantom. In the AE framework, this work highlights the necessity of considering the propagation angle, since the evolution of the SH mode wave speed with stress depends on that angle, and contributes to refining the AE theory in TI quasi-incompressible media.

We perform THz generation by optical breaking in air, with a helium gas flow blown perpendicularly to optically induced filament. The gas flow modifies both the magnitude and polarization of the radiated THz field, due to 1) the different optical/THz properties of air and helium; 2) the weaker optical/THz generation efficiency of helium; 3) the different nonlinear optical properties of both gases. We develop a model that fits the experimental data and permits us to estimate the second order nonlinear dispersion of He relatively to the one of air.

Novel schemes to achieve surface-emitting multi-and nearly single-cycle THz generation by optical rectification in two-dimensional quasi-phase-matching (2-D QPM) structures are proposed. Placing 1-D phase mask in front of a conventional 1-D periodically poled lithium niobate (PPLN) crystal forms the periodic pattern that is directed perpendicular to the existing PPLN’s grating vector. It is shown that the scheme enables multi-cycle THz pulse generation with 0.37 MW power and 24 μJ energy at a pump pulse energy of 3.4 mJ.

Spatio-temporal terahertz electric field profiles around 35 MeV electron bunches propagating in the air are measured by the echelon-based single-shot electro-optic measurement with a sub-picosecond temporal resolution. We demonstrates that the Lorentz contraction of the electric field in the direction perpendicular to the pass of the electron beams is directly observed.

We investigate TM-wave propagation over an impedance-matched graded interface between a right-handed material (RHM) and a left-handed material (LHM) with graded permittivity and permeability. We assume a lossy case with permittivity and permeability profile changing according to a hyperbolic tangent function along the direction perpendicular to the boundary plane between the two materials. A remarkably simple exact analytical solution to Helmholtz equation is obtained. The exact analytical expression for the field intensity along the graded LHM-RHM structure confirms the expected properties of LHM media. Furthermore, in the special case of normal incidence, we reconfirm that there is an excellent agreement between the present analytical results and numerical simulations.

A Thermally Actuating multi-layered tunable aperture for distance sensing is proposed to measure distance to the obstacle. This tunable aperture uses metal of high thermal expansion to make different aperture size by Joule’s heating which operates when the voltage is applied to two copper metal structure. This aperture consists of eight thermal actuators that can obtain 3D image and distance information in a single camera simultaneously. The distance data can be obtained by Depth from Defocus method which compares blurriness of two images from each aperture size. The proposed thermal actuator is chevron type that has two beams that are slightly bent from each other to amplify the displacement of aperture perpendicularly. To find the exact displacement, COMSOL MULTIPHYSICS simulation tool was used. The device was fabricated with MEMS technology with two masks, and aperture was formed by bonding four identical layers with 45 degrees to each other to create octagonal shape. The dimension of thermally actuating part is 10mm by 100um by 40um and overall dimension is 10mm by 10mm by 2.2mm. The measurement result shows that the average displacement of 462um was obtained when 7.2V was applied which makes the aperture size from 546um to 1008um.

In this work, we propose a compact broadband cylindrical dielectric resonant antenna working from 1.8GHz to 2.2GHz. First, based on two kinds of orthogonal models, we get a dual-polarized broadband antenna with a wide relative bandwidth of 20%. Then, with the proposed antenna structure, the cross polarization highly decreases. Specifically, the cross-polarization discrimination (XPD) can reach 18dB at 2.14GHz and 14dB at 1.84GHz in bore-sight direction. Finally, in such a compact size of 0.2 λ, the isolation between two ports improved by the metal post can reach 15dB on average with its minimum value of -40 dB at 2.05 GHz. The simulation verifies that the maximum radiation direction is perpendicular to substrate with the total gain of 6.4dB at 1.84GHz and 6.9dB at 2.14GHz. Thus, the characteristics of compact aperture and dual-polarization makes that the antenna can be used as miniaturized base station antenna.

This paper proposes a dual-polarized omnidirectional antenna for 2G/3G/LTE/5G-C band applications. The antenna mainly consists of a vertically polarized (VP) element and a horizontally polarized (HP) element. The HP element is composed of four printed dipoles and a four-way power divider, whereas the VP element is made up of two copper pieces that are placed perpendicular to each other. Simulation results indicate that the overlapping bandwidth of the dual ports is 74.3%(1.65-3.60 GHz). In addition, the port isolation is larger than 20 dB and the gain variations are within 3 dB in both the VP and HP planes.

Alfven waves have long been thought to resonantly accelerate auroral electrons [1] . The acceleration process is hypothesized to involve inertial Alfven waves, which have typical length scales perpendicular to the background magnetic field B 0 comparable to the electron skin depth [2] . At these perpendicular scales, inertial Alfven waves have an electric field component parallel to B 0 that could resonantly accelerate electrons to auroral energies. The Polar and FAST missions have identified a statistical coincidence between Alfven waves, accelerated electrons, and auroras [3] , [4] . Simulations have detailed the motion of an ensemble of test particles and identified the characteristics of an accelerated population.

In this paper a dual polarized beamforming phased array antenna for millimeter wave application has been presented. Aperture coupled antenna is designed with two patches (and two stacked patches or parasitic patches below them) fed by one main line by bifurcating into two parts for these patches. The top patches are bigger compared to stacked patches below them. Under these patches two "I" shape perpendicular slots (of different sizes) has been created in the ground plane for each polarization. One is for horizontal and another for vertical polarization. The designed antenna operates at 28 GHz with peak realized gain around 8.3 dBi over a band of 25 GHz to 29 GHz in vertical polarization and peak gain of 8 dBi for 25.9 to 29 GHz in horizontal polarization. The antenna can be widely operated over the band with isolation between these ports 30 dB.

This paper reports a magnetic-drive force-distance curve-based atomic force microscopy using an orthogonal cantilever probe (OCP), which can study the interactive effects between sidewall morphology and adhesion force. The OCP is composed of a horizontal arm and a vertical arm with a protruding tip, in which a ferroferric oxide bead is used to connect them orthogonally together. Based on this unique structure, the designed OCP can detect the interaction force between the sidewall and tip through torsional deformation, thus mapping steep vertical surface. The ferroferric oxide bead is magnetized along the direction perpendicular to the long axis of the horizontal arm, becoming a magnetic bead, in order to provide vibration at off-resonance for the OCP. Relevant theoretical analysis and calibration tasks are introduced at first, and then, two specimens including a micro-electro-mechanical system device with micro-comb structure and a microarray unit are adopted to verify its practicability of the proposed method. Experimental results show that there is a correlation between sidewall adhesion and surface roughness, in addition, these performance parameters can also be meaningful for the micro-operation process.

Magnetic tape is used for deep archival storage as a means of storing large amount of infrequently accessed data. Current magnetic tape media consists of a random assembly of small Ba-Ferrite particles encapsulated in a polymeric film coated on a 5 micron-thick plastic substrate. The areal density in current tape products is about 11 Gb/in 2 . Latest particulate media recording demonstrations have achieved 123 Gb/in 2 with 1600nm 3 BaFe particles and 317 Gb/in 2 with 950nm 3 strontium ferrite particles [1] , [2] . Hard-disk drives (HDD) have been using thin-film magnetic media for more than 40 years and current perpendicular magnetic recording technology in HDD products has achieved recording densities up to 1 Tb/in 2 . As a result, there has been a strong interest to use sputtered thin-film media technology for tape recording. Recent developments in sputtered perpendicular magnetic recording thin film on tape have demonstrated recording densities up to 201 Gb/in 2 [3] - [5] .

Spin transfer torque magnetoresistive random access memory (STT MRAM) is an alternative to SRAM [1] and Flash [2] , [3] in various embedded applications, as it can provide non-volatility concurrently with low power, high speed operation, and high endurance. In order to become a viable option for replacing DRAM as a stand-alone memory at relevant areal densities, further optimization of MRAM performance is needed, as continued technology scaling and advanced computing systems impose challenging specifications on MRAM in terms of its retention (thermal stability), read-out latencies, and write margins [4] . This talk will present our recent experimental, theoretical, and modeling results on understanding physical mechanisms that affect performance of perpendicular STT-MRAM cells under electrical, magnetic and thermal excitations. In particular, we will report experimental and modeling results that extend of our recent work on electrical self-heating in STT-MRAM [5] to smaller device size, describe our work on optimization of FL materials for improving STT efficiency and thermal stability [6] , present analytical model for calculating energy barrier for domain-wall-mediated magnetization reversal of the perpendicular FL [7] , and show our experimental results which suggest that, contrary to common understanding, fitting the magnetic-field switching probabilities P(H) to a macrospin-reversal model provides approximately correct values of perpendicular magnetic anisotropy field H k on device level.

This paper proposes the design of a frequency and polarization reconfigurable slot antenna with surface pins(S-PINs). The basic structure of the antenna is two perpendicular slots with S-PINs. The antenna can realize frequency reconfigurable and polarization reconfigurable, using four S-PINs. The simulated gain at the C and K band are 4.32dBi and 5.2dBi, at 5.76GHz and 18.072GHz, respectively. In this paper, the characteristics of the antenna are verified through simulation, and shows that it can be frequency reconfigurable and polarization reconfigurable.

The automated image-based robust estimation of crack widths in concrete structures forms a significant component in the automation of structural health monitoring. The proposed method, called rectangle transform, uses the gray-scale profile extracted perpendicularly to the direction of crack propagation. Based on the concept of an idealized profile, it transforms the empirical profile into an equal-area rectangle from which the width is inferred. On the available dataset and compared to two other approaches, it shows at least par performance for widths larger two pixels and distinctly better performance on widths smaller equal two pixels. Moreover, it is more robust towards blurred input.

The complex shallow sea topography will lead to stronger three-dimensional (3D) acoustic effect. The direct numerical simulation of 3D shallow sea sound field under seamount environment is carried out by using the Finite Element Method (FEM). Taking acoustic transmission loss as the research object, the influence of seamounts on the propagation of low frequency acoustic signals in shallow sea in the range of kilometers is analyzed by controlling the seamounts' cross section and the sound source frequency. The simulation results show that the increase of the seamount radius in the direction of the source axis will decrease the blocking effect and increase the backscattering effect. The increase of the radius of seamount in the direction perpendicular to the source axis will increase the 3D scattering effect at azimuth obviously. At the same time, with the increase of the source frequency, the 3D scattering effect will gradually increase.

We present the design of a new inductive proximity sensor to detect metal targets and their direction of movement. The proposed sensor design includes a base board with the necessary microcontroller based circuitry for driving and reading the sensing LC tanks and several different solutions for the printed sensor coil. Different coil configurations are fabricated on separate printed circuit boards designed to plug-and-play into the base board. They are intended for different specific applications including for sensing metal targets approaching perpendicularly on the coil plane and for sensing and identifying the lateral direction of movement (i.e., left-to-right or right-to-left). The coil designs are studied via simulations using the freely available Numerical Electromagnetics Code (NEC). A complete hardware prototype is developed and demonstrated to detect different metal targets, including copper, brass, aluminum, and stainless steel. It is also shown that measurements obtained from hardware experiments are in good agreement with the simulations.

The numerical simulations of this paper present the flow structure of an isothermal cylinder with curved corners r/R = 0.5, where R is the half-width and r is the corner radius of the cylinder, with varied angle of attack, α (0° ≤ α ≤ 45°). The cylinder is located perpendicular to the air stream flow with Re = 180 and Pr = 0.7. The solution of the governing equations obtained using ANSYS-FLUENT package. The variation of α from 0° to 45°, leads to two major flow regimes A and B. The flow regime of type A appears at small range of α (0° ≤ α < 10°), can be termed as trailing corner separated flow. The flow regime of type B appears within the large range of α (10° ≤ α ≤ 45°), can be termed as leading-trailing corner separated flow. The flow structure is unsteady and characteristic by alternating Karman vortices appears for each α. The maximum vorticity ${\left| {{\mathbf{w}}_z^{\ast}} \right|_{\max }}$ is inversely linked to the wake bubble length $L_b^{\ast}$. The lower core (positive) instantaneous vorticity increases with increasing α with slight increasing for α = 0° - 5° and 30° - 45°, while large increasing for α = 5° - 30°.

In neurosurgery, bipolar forceps is used to coagulate and dissect brain tissues. As in robot-assisted neurosurgical scenario, force perception on bipolar forceps can quantify intraoperative contacting forces between tips of forceps and brain tissues. The quantified tool-tissue contacting force information can help quantify experts experience and ensure safety of robot-assisted surgery. It is challengeable to facilitate the forceps with forces sensing ability because of the limited space for installing sensors. The craniocerebral tissues, interstitial fluids and currents passing though polar of forceps also bring restrictions on force sensing methods. In this article, we propose a planar force perception method to collect force information on bipolar forceps tips in real-time by installing two Fiber Bragg Grating Sensors (FBGs) perpendicularly on each polar of bipolar forceps. FBGs are free from electromagnetic interference. The slim configuration and silicon materials of FBGs make it a suitable sensing method for little disturbance on working state of bipolar forceps. In experiments, axial forces and planar forces were monitored in real-time. It is possible to sense forces at a minimum of 0.01 N. The calibrating revolution on x, y axis is 0.01, 0.03 N, separately.

Quartz Crystal Microbalance (QCM) is a high-sensitivity piezoelectric sensor that enables it to detect loads in the nanogram order. QCM usually consists of a thin quartz plate with an AT-cut orientation. At the beginning of its development, research on QCM was carried out using an experimental approach. In experiments, it is quite difficult to create the ideal system, which often neglects several important factors so that the experimental results are very prone to errors. The Finite Element Analysis (FEA) can be a solution to overcome some of the shortcomings in the experimental method. In this paper, a study was conducted on mesh variations on the QCM sensor simulation. It is very important to determine an accurate and efficient mesh. The hexagonal mesh was used with mesh variations in XY-direction (parallel to the QCM surface) and Z-direction (perpendicular to the QCM surface). The resolution of the mesh in the Z-direction has more impact on the resonance frequency of QCM. Whereas the resolution of the mesh in the XY direction has more impact on the details of the deformation pattern in the QCM vibration mode.

The refractive index derives its name from the property that it determines how much a beam of light bends (or refracts) when it passes from one material to another. This relationship is expressed by Snell’s law, which has the form n 1 sin θ 1 = n 2 sin θ 2 and is illustrated in part (a) of Fig. 1 . From the form of Snell’s law, we see that if n 1 is equal to zero, then for any angle of incidence θ 1 then angle of refraction θ 2 will be equal to zero, as illustrated in part (b) of the figure. As a consequence, light can leave a zero-index material (ZIM) only in a direction perpendicular to the surface of the material. A basic law of physics states that light rays are reversible. For example, if a light ray can travel from medium 1 to medium 2 along a certain path, it can travel from medium 2 to medium 1 along the same path, but with the directions reversed. We thus see that light can enter a ZIM only from a direction perpendicular to the surface of the material.

Ultrasonic powering is an emerging power source for implantable microdevices due to its superior efficiency in energy transfer at millimeter-scale, long operation distance, and near omnidirectionality. In this paper, we investigate a novel polyhedral ultrasound transducer with emphasis on angular alignment between piezoelectric poling vector and incident waves. Three different polyhedrons (i.e., sphere, octahedron, and dodecahedron) are fabricated via 3D printing lead-free barium titanate ceramic. The maximum output voltage for a unit area occurred at 0° when the poling and waves direction aligned, which were measured to be $0.677\pm 0.071,1.058\pm 0.049$ , and $0.709\pm 0.092\ \mathrm{V}$ , respectively. At the extreme angular misalignment at 90° (poling and waves perpendicular to each other), only the dodecahedron could sustain the voltage output with 21% reduction, whereas sphere and octahedron dropped by 46%. The results imply that the geometry factor may overcome the poling vector, enabling omnidirectional ultrasonic powering for implantable microdevices.

Lamb waves have the advantages of long propagation distance and low power loss, which are widely used in the field of structural health monitoring. However, the Lamb waves generated by conventional methods usually contain various modes, and the multi-modes Lamb waves always cause troubles for damage detection and localization. This research proposes a novel single-A0 mode Lamb wave generation technique: the actuator is attached on the side face of the beam structure, and the sensor is attached on the top or bottom surface, which is perpendicular to the side face, so the single-A0 mode Lamb wave can be generated. Due to the mode conversion effect of Lamb wave when it passes through a crack, the existence of crack can be determined by checking the existence of S0 mode. In addition, the location of the crack can also be localized accurately using the proposed algorithm. Numerical and experimental investigations are carried out to demonstrate the performance of the proposed method.

International audience; In this study, we theoretically investigated the electronic properties of resonant tunneling diodes (RTDs) grown along the polar and non-polar orientations by using the self-consistent solution of the coupled Schrödinger and Poisson equations. Based on the transfer matrix formalism, the effects of the geometrical parameters on the current-voltage characteristics of Al0.2Ga0.8N/GaN RTDs we analyzed by varying GaN well width and Al0.2Ga0.8N/GaN barrier thicknesses. The results show that the characteristics of polar and nonpolar Al0.2Ga0.8 N/GaN RTD strongly depend on the barrier and well size; showing a strong decrease in peak and valley current density and a large PVR enhancement when increasing well and barrier thickness. To bring interesting RTD electrical characteristics, a comparison between the polar and non-polar Al0.2 Ga0.8N/GaN RTD was performed. non-polar oriented RTDs show better electronic characteristics, including higher peak current density (Jpeak), smaller peak voltage (Vpeak), and greater pic-to-valley ratio (PVR), than polar ones.

The design, development and assembly of microcontroller based Dual Axis Solar Tracker to enhance the performance of an immobile Solar Photo Voltaic (SPV) panel is presented in this paper. Four Light Dependent Resistors (LDRs) act as sensors to determine the intensity of sunbeams and communicate the same to Arduino UNO’s microcontroller. Depending on the command given by Arduino Uno’s microcontroller, the solar panel is being tilted perpendicular to the incident sun’s rays by using two servomotors. Thus, the developed prototype ensures that the efficiency of photovoltaic panel is increased in comparison to static solar photovoltaic panel.

Fine pitch electronic components in the defense and aerospace applications, experience high thermo-mechanical loads. To study and understand these scenarios, the printed circuit boards with components are usually tested at 0-degree drop angle. But the angle of shock varies a lot in real life scenarios. Change in drop angle, could change the mode of shock propagation throughout the board, which further affects the solder-joint reliability of the components on the board. Studying board level drop tests with change in drop angle would be more relatable to the real-life drop scenarios. Potting is one of the most cost-effective restraint mechanisms, it protects the components from shock, vibration, moisture and heat. Exposure to high temperature is very common in these applications. But properties of the potting compounds changes with long term exposure to high temperature. Potted test vehicles are exposed to a temperature of 100C for 30 and 60days. Long term storage at high temperature, is intended to help in understanding the change in potting compound properties and their impact on reliability. A circular board with surface mount components is tested at g-levels of 10,000g and 25,000g and three different angles of 0-degree, 30-degree, 60-degree. Understanding effect on shock-propagation and component reliability with respect to drop angle variation and long-term thermal aging, is the focus on this paper. To make simulation predictions of the drop angle variation, an explicit finite model of the drop assembly has been created to predict and compare with the experimental results.

In this paper, dynamic wire sweep in a package during molding is analyzed with Fluid Structure Interaction (FSI) modeling, as well as an experimental validation. Wire bonding (WB) is widely used in integrated circuit (IC) packaging, connecting between chips and substrate. Subsequent molding fluid flow with a certain viscosity and with a certain speed perpendicular to wire curve easily sweeps wires, leading to potential electrical failure. Wires are as thin as tens of micrometers to enable more input-output on a limited chip area. Compared to tens of millimeters in package scale, hundreds of wires are not feasible to model in a package model due to meshing limit. This paper uses an overall flow model considering non-Newton fluid characteristics, from which fluid velocity field is taken as boundary of wire submodel. Overall model contains compound curing kinetic property to capture epoxy reaction during flow because epoxy gelation time is not long. The submodel considers solid-fluid coupling with FSI, as well as thermoset material property, therefore, narrow gap filling around wires and chips could be evaluated. Experimental wire sweep shows consistency with FSI submodel, while non-FSI method could not capture wire sweep in narrow tunnel of compression molding. Curing thermoset material also prevents wires from recovering back elastically. Factors such as wire size, speed, and wire distance are simulated for package design. Results show wire-to-wire distance couples with wire size and impacts on sweep, which could be optimized at design stage with FSI simulation. Small distance may introduce filling issue as molding fluid contains fillers. Front wire may not be able to protect its back wires if their distance is too long. Thicker wire, lower wire loop, and lower inlet speed would help to minimize wire sweep.

Approaches for automatic computing footprint Chippaux-Smirak Index by using Curve Slope Estimation and Perpendicular Line Detection methods are proposed in this paper. First, the k-mean clustering and the Circular Hough Transform approaches are applied to divide the footprint image into left and right sides and then removed the toe prints. Then, the horizontal integral intensity projection method is applied to obtain the position of the anterior and the posterior aspect of the toeless footprints. All boundary points of the footprint are located by the Morphological Gradient method. Subsequently, the slope of a curve at the point of tangency and the straight-lines which plane of the Lateral Calcaneal on the outside of the footprint image are then estimated. Finally, the length of the straight-line at the narrowest point on the foot arch, the length of the straight-line at the widest point at the metatarsals, and the footprint Chippaux-Smirak Index value were calculated by applying the Euclidean method. Footprint arch type are then classified by using the cutoff value of the Chippaux-Smirak Index. In this experiment, the average accuracy for automatic computing Chippaux-Smirak Index values in the footprint image is 90.17% and the accuracy for classification of the footprint arch type is 87.86% in comparison with the manual computation from the expert.

The polarization states of a semiconducting ferroelectric film have been analyzed in terms of the Landau-Ginsburg-Devonshire thermodynamic model supplemented with a drift-diffusion equation for electrons. For definiteness, an undoped epitaxial PZT film containing charged oxygen vacancies and electrons is considered. The polar axis is perpendicular to the film plane. It is shown that, for the same parameters and boundary conditions at the contacts, the film can be in one of four basic states: two classical states with positive or negative polarization and two tail-to-tail (TT) and head-to-head (HH) domain states. The condition for the existence of TT and HH domains in a film with finite thickness is obtained. It is shown that the TT and HH domains originate from the unstable part of the theoretical Landau S-curve P(E). The total free energies of different states of the film are compared and the hysteresis loops and the transformation of the HH and TT domains to the classical polarization state under a rectangular voltage pulse are discussed.

This paper presents a method for estimating how the driver of a vehicle can use braking or acceleration to avoid the collision with a moving vehicle. Approach relies on a novel threat assessment module, which combines prediction and avoiding collision maneuver. We describe Braking Threat Number (BTN), Acceleration Threat Number (ATN), Deceleration Threat Number (DTN), and Steering Threat Number (STN). A collision avoidance by braking system, based on proposed method has been evaluated on simulated traffic scenarios at intersection. Our simulation shows that autonomous braking can be initiated 1 to 3 seconds before the potential collision. With this system the vehicle will have less impact collision.

To improve the matching design of safety and arming device parallel to the projectile axis with micro detonation sequence and plastic deformation under setback force, a MEMS safety and arming device with a latching mechanism placed perpendicularly to the projectile axis has been proposed. The proposed device is more beneficial to increase the force area of mechanism and to reduce the energy loss of micro detonation. The motion of the latching mechanism under dual environmental forces is theoretically modeled, and the criteria of reliable latching are given. Furthermore, dynamic finite element simulations are carried out to study the motion characteristics under dual environmental forces. The rerults in simulations indicate that the latching mechanism can achieve latching reliably under the rotary speed of 7000–18000 rpm with no plastic deformation.

Anisotropic spreading of droplets on a heterogeneous solid surface is important for fundamental research and industrial applications. Compared to structurally and chemically heterogeneous surfaces, electrowetting could control the surface free-energy landscape of the solid-liquid interface dynamically with the applied voltage. In this work, we study the anisotropic spreading of droplets on striped electrodes (interdigitated electrodes) with voltages applied. The contact angles and contact radii of the contact area observed parallel and perpendicular to the striped electrodes are presented quantitatively. Our research may help the understanding of droplet spreading in heterogeneous electric fields and assist in the applications of electrowetting.

Magnetic tunnel junctions (MTJ) are engineered with the film stack of crossed magnetization pattern structure for perpendicular tunnel magneto-resistance (TMR) sensor application. The fabricated devices show good linearity and stability. The temperature dependence and the noise level of the sensor are also characterized. We demonstrate that the sensitivity and linear range of the perpendicular pinned TMR sensors can be tuned in quite a large range by controlling the free layer thickness. This research provides guidance for the design and process optimization of the perpendicular sensors.

Electrical aging limits the reliability of crosslinked polyethylene DC cable. The study on the reaction kinetics of electrical aging is an important basis of improving the reliability of DC cable. Free energy increment (FEI) under electric field reflects the reaction rate of electrical aging, which is very useful to analyze the aging characteristics of materials. However, there is no direct way to get the FEI, which causes that the FEI stays at the stage of theoretical analysis and cannot be obtained by experiment. In this paper, an easy method including experiment and calculation to get the FEI is proposed, and a simulation method to obtain the FEI is also introduced. The experiment and simulation both show that the FEI of crosslinked polyethylene (XLPE) is proportional to the degree of polymerization, is approximately linear with the electric field, and grows with the temperature. According to the FEI obtained, we find that the molecular branches of the XLPE whose plane of carbons is perpendicular to electric field are more likely to age. Improving molecular chain orientation and reducing the length of branches are two of the methods to improve the aging characteristics of the XLPE.

Microwave assisted magnetic recording (MAMR) is one of the promising next generation recording technologies that is expected to carry the magnetic recording industry beyond today's perpendicular magnetic recording (PMR) limit. MAMR involves the introduction of a high frequency oscillating magnetic field in the microwave frequency (GHz) range at the time of writing. This assisting energy at a specific frequency helps to make the magnetic grains more malleable and thereby reverse more easily which permits the usage of smaller, higher coercivity grains in the media, supporting a higher recording density. The generation of a stable oscillating magnetic field is expected to come from a spin-torque oscillator (STO) that has a rotating field-generating layer (FGL) when a current is injected. The STO must be properly designed in order to generate the stable oscillating magnetic field of the desired frequency and with sufficient amplitude to assist in the media reversal. In this work, we optimize the STO to produce a large and stable oscillating field with the desired parameters. Micromagnetic simulations of the STO are used to determine the STO's behavior and we propose various metrics to be used as a measure of the performance of the STO's response. Subsequently the response surface methodology (RSM) is employed to optimize our selected performance metric, producing the highest performing STO.

A new design of a MEMS Energy Harvester (EH), based on an arched microbeam with electrostatic transduction, is proposed in this paper. The design consists of a single transducer composed of two masses designed to move in perpendicular directions and linked by the arched microbeam. Thanks to the proposed design the axial motion is converted and amplified into a perpendicular motion and vice versa. We derive a mathematical model by presenting the governing equations of the coupled electromechanical system. A static Finite Element analysis is also performed to validate the reliability of the proposed device and showed that a 10 times amplification can be achieved for the input motion. The solved analytical dynamic analysis demonstrates the practicability of the device for different in plane directions of the excitation. For optimal conditions it was shown that the initial polarization voltage can be doubled for a 20 s excitation.

Magnetoresistive sensors are usually used to measure the magnetic field with the direction parallel to the plane of the magnetic sensor, but a soft magnetic permalloy flux concentrator is integrated in the sensor, and can change the direction of the magnetic field in the magnetic sensor, so that the magnetoresistive unit can also measure the magnetic field (the Z axis) perpendicular to the plane of the magnetic sensor. The magnetic concentrator is usually made of permalloy with high magnetic permeability. The flux concentrator is designed into a grid structure, the magnetic field (the Z axis) perpendicular to the sensing plane of the sensor can generate the magnetic field component in the sensor plane (the XY axis), and the giant magnetoresistance (GMR) magneto-sensitive unit located under the magnetic concentrator can measure the Z-axis magnetic field. The GMR magneto-sensitive unit is composed of four bridge arms, which are connected by metal conductive materials to form a Wheatstone bridge structure. The two magneto-sensitive units on the opposite bridge arms of the bridge are located on both sides of the soft magnetic grid respectively and form the push-pull structure under the action of the magnetic field, so that the strength of the output signal of the sensor is doubled, and the vertical packaging form of the conventional Z-axis sensor is also prevented. According to the experimental results, the sensitivity of the Z-axis giant magnetoresistance sensor with this structure can reach 0.8 mV/Oe, and the magnetic field measurement range can reach 150 Oe. It can be used in various fields such as geomagnetic measurement and current measurement.

A new microfabricated gas chromatography column (µGC-column) called semi-packed column embedded high density elliptic cylindrical posts (SPC-HDECPs) was reported in this paper. There are six elliptic cylindrical posts in the cross-section perpendicular to the gas flow in the 250 μm-wide straight silicon microchannel of SPC- HDECPs. Compared to semi-packed columns with cylindrical posts (SPC-CPs) in identical micro-channel at the same effective width (130 μm), SPC-HDECPs have a 327% improvement in the number of theoretical plates of the octane due to the surface area is increased by 71%.

This paper presents measurement of a microstrip antenna array fed by longitudinal slots on a narrow wall of the rectangular waveguide with standing wave excitation for linear polarization perpendicular to the axis. A dual-ring microstrip antenna with a circumference of 5 wavelengths excited by the longitudinal slot on the narrow wall of the waveguide with a dielectric substrate is used as an element of the proposed array for grating lobe suppression due to the longitudinal slots arrayed at a spacing of one guided wavelength. In this paper, a prototype array consisting of the dual-ring microstrip antennas fed by three longitudinal slots on the narrow wall of the rectangular waveguide with standing-wave excitation is designed and fabricated. The measured results are agreed with the simulated ones obtained by HFSS. The measured radiation pattern reveals that grading lobes due to the longitudinal slots are well reduced by the proposed array. Validity of the design of the proposed array is confirmed by the measurement.