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Objectives The deviation in gait cycle due to trunk acceleration and muscle activity on even and uneven inclined planes should be analyzed for the design of lower limb exoskeletons. This study compares the gait variability of gastrocnemius and medial hamstring muscle activity variation of twenty young male adults on inclined even and uneven planes. Material and methods The individuals walked on a long, 10° inclined even and uneven plane in both up-the-plane and down-the-plane directions at their preferred speed (average speed is 1.2 m/s). Gait variability during walking was calculated using an average standard deviation of trunk acceleration and the significance of change was calculated using two-way-ANOVA. For studying the difference between integrated electromyography (IEMG) values of walking on even and uneven planes, two parameters Normalized IEMG Percentage (NIP) and IEMG Variation Percentage (IVP) were chosen for the analysis. Results The results strongly agree with the hypothesis that gait variability hikes in the vertical direction of subject with a p-value of 0.04. The IEMG range of medial-hamstring muscle while walking on even and uneven plane is not highly significant for swing (0.44) as well as stance phase (0.47). While walking on an inclined uneven plane, the response of gastrocnemius muscle indicated the variation of NIP between 14.31% to 64.63%. It was observed that NIP and IEMG values of medial-hamstring muscles during backward walking have a resemblance. Conclusion Trunk variability had a significant change in the vertical direction (V) and was insignificant in medial-lateral (ML) and anterior-posterior (AP) orientations for both even and uneven inclined planes during forward and reverse walking. The muscle activity of gastrocnemius and medial-hamstring muscles does not have sound variations while walking on the inclined uneven plane.

This article investigates the properties, from a nonlinear control system standpoint, of atomic force microscope (AFM) systems, whenever operated in contact mode and controlled in the vertical direction by proportional-integral control law. By modeling the AFM as a system in which a piezo-electric actuator and a cantilever mutually interact in order to produce the sample topography, ensuing distortions affecting the quality of the yielded topography measurement are naturally cast and analyzed. The proposed investigation considers distortions due to the inception of hysteresis and vibrational dynamics within the piezo-actuator or provoked by system saturation. Both hysteresis and saturation are inherently nonlinear phenomena and are modeled as such. In spite of the inherently nonlinear nature of the AFM dynamics, investigations of the contact mode case from a nonlinear standpoint are lacking within the AFM literature. As the topography yielded by the AFM completely relies on its control algorithm, to the point that the measurement itself corresponds to the control action v(t), it becomes of paramount importance to understand how v(t) relates to the actual topography, and how such a relationship is affected by the aforementioned distortions. This article hence intends to contribute to the AFM literature, by providing a study in which the very meaning of the image measurement yielded by the AFM is investigated, in the light of distortions due to nonlinear phenomena. The AFM is considered to be operated in contact mode with a PI algorithm. Furthermore, as a byproduct of the derived nonlinear stability analysis, a novel, model-based algorithm for tuning the PI control gains is provided. Finally, experimental results are presented and analyzed in view of the derived theory.

A theoretical sea echo modeling of the floating-platform high-frequency hybrid sky-surface wave radar (HSSWR) is presented. The ionosphere is considered to be a no-tilt reflecting plane moving in the vertical direction. Subsequently, the first-order sea clutter cross section with consideration of the platform sway and yaw motion is derived. Simulations are conducted to explore the influences of the ionospheric movement and the platform oscillation motion on the sea clutter power spectrum. Simulation results indicate that the platform sway motion may induce additional peaks that distribute symmetrically concerning the Bragg peaks, while the platform yaw motion and the ionospheric movement may broaden even split the sea clutter. Experiments are conducted with the newly-developed HSSWR system, of which the receiving arrays are simultaneously deployed on a floating platform and the shoreside. Experimental measurements concerning the frequency shift, Doppler width, and the arrival angle of the E-layer/F-layer ionosphere reflected direct wave are compared and analyzed. The study demonstrates the feasibility of the proposed modeling and provides valuable guidelines for the sea clutter characteristics analysis and the data quality assessments of the floating-platform HSSWR.

This letter proposes a hybrid decoupling structure consisting of a neutralization dielectric board, metal baffle, and feeding network to enhance the isolation in a compact large-scale base station array. Both the neutralization- and partition-based schemes are utilized to reduce the mutual coupling between antennas. The neutralization dielectric board provides a new signal path to cancel the original mutual coupling, and the metal baffle is employed to suppress the propagation of the space electromagnetic wave. The antenna elements in the vertical direction are excited by a feeding network. A 44 dual-polarized antenna array with a horizontal edge-to-edge distance of 0.38 free-space wavelength is designed and fabricated to demonstrate the effectiveness of the proposed structure for large-scale arrays for base station application. Simulated and measured results show that the voltage standing wave ratio is less than 1.7, and the isolation between any two ports in the array is better than 20 dB within the entire operating frequency band. Stable radiation patterns with a good front-to-back ratio and cross-polarization ratio are achieved.

Rain streaks showing in images or videos would severely degrade the performance of computer vision applications. Thus, it is of vital importance to remove rain streaks and facilitate our vision systems. While recent convolutinal neural network based methods have shown promising results in single image rain removal (SIRR), they fail to effectively capture long-range location dependencies or aggregate convolutional channel information simultaneously. However, as SIRR is a highly illposed problem, these spatial and channel information are very important clues to solve SIRR. First, spatial information could help our model to understand the image context by gathering long-range dependency location information hidden in the image. Second, aggregating channels could help our model to concentrate on channels more related to image background instead of rain streaks. In this paper, we propose a non-local channel aggregation network (NCANet) to address the SIRR problem. NCANet models 2D rainy images as sequences of vectors in three directions, namely vertical direction, transverse direction and channel direction. Recurrently aggregating information from all three directions enables our model to capture the long-range dependencies in both channels and spaitials locations. Extensive experiments on both heavy and light rain image data sets demonstrate the effectiveness of the proposed NCANet model.

In this letter, we explore the feature of coprime linear array (CLA) motion for enhanced array aperture and higher degree of freedom (DOF) by implementing synthetic aperture processing. Since the traditional fixed CLA cannot achieve two-dimensional (2-D) DOA estimation, we propose a novel approach to construct the virtual coprime planar array (VCPA) just by the CLA motion. Specifically, the CLA moves along the vertical direction at a constant velocity and the two subarrays of CLA are controlled to snap at different time delays related to the coprime number of sensors, by which the received signals at different time delays are synthetically processed to construct a VCPA. Simulation results demonstrate that: a) our proposed approach outperforms the synthetic CLA moving along the direction of layout of the initial arrays on DOF and the dimension of DOA estimation; b) the proposed VCPA can achieve 2-D DOA estimation just by the motive CLA and achieve no worse performance than the practical coprime planar array but by using fewer sensors.

The full-waveform hyperspectral light detection and ranging (FWHSL) data have been widely used in surface topography, vegetation detection, and 3-D urban terrain modeling, capable of revealing the spatial distribution of a target and more detailed spectral information in the vertical direction. However, the echo signals of a target would significantly vary between different spectral channels due to the reflectance characteristics and the uneven energy distribution of supercontinuum laser source. Especially, band channels with weak reflectance over a long distance would affect the extraction accuracy of waveform parameters, which are essential for retrieving the spatial and spectral information of targets. This article proposes a multichannel interconnection decomposition method to improve the extraction accuracy of distance and spectral information at each pulse using hyperspectral waveform data. Two experiments were conducted to verify the performance of long-distance detection of targets using FWHSL. The first experiment detected a standard whiteboard, a green leaf, and a yellow leaf at roughly 518 m. Results demonstrated a considerable improvement in ranging precision and spectral detection using the proposed method compared with using the optimal channel with the best data quality. The second experiment simultaneously detected two adjacent targets at a distance of approximately 518 m. Results presented clear superiority of adding waveform channels in terms of discovering overlapping components and retrieving accurate waveform parameters. The success rate of extracting two targets 60 cm apart was greatly increased from 47% to 73% through the multichannel interconnection waveform decomposition (MIWD) method.

The drainage of granular assembly from a flat-bottomed silo can be in either funnel flow mode or mixed flow mode. The primary motivation of this work is to investigate whether there exist fundamental differences between the rheological behavior of particles under these two discharge modes. The developments and evolutions of flowing zone and also the characteristics of particle velocity fluctuation during funnel and mixed flow discharges were analyzed and compared by performing 3D Discrete Element Method (DEM) simulations. For funnel flow discharge, the characteristic width of flowing zone at the early discharge state presented a clear history-dependent feature. For mixed flow discharge, the flowing zone sharply shrunk when the upper free surface of the material approached a critical height and the discharge mode then shifted to funnel flow mode. Discrete Fourier transform results demonstrate that resonant motion of particles appeared during both funnel and mixed flow discharges. The correlation analyses indicate that for these two flow modes, there both existed an intermediate region in the converging part of the flowing zone. Its upper boundary located at the position where the flowing zone started to converge along the vertical direction and was featured as the maximum particle compressive force. And its bottom boundary corresponded to the location of free-fall arch and acted as the source of the resonant motion of particles. Our simulation results thus suggest that from the perspective of particle velocity fluctuation, there is no essential difference between granular flows under funnel and mixed discharge modes.

We propose that the use of tightly stacked three-dimensional (3D) diamond-shaped Ge nanowire (NW) gate-all-around field-effect transistor (Ge-NW GAAFET) is a feasible approach to continuous scaling. The proposed devices with the Al2O3 dielectric exhibit high ISAT of 1200 μA/μm (pFET) and 1100 μA/μm (nFET), high ION/IOFF ratio of approximately 1×105, and steep subthreshold swing (SS) close to 70mV/dec. Superior gate control of the Ge-NW GAAFET was confirmed by the 3D TCAD simulation for the sub-3nm node applications. The formation of the tightly stacked Ge NWs is fully compatible with the complementary metal oxide semiconductor (CMOS) technology platform using only alternating isotropic and anisotropic dry etching, thus showing promising potential for extending CMOS scaling in the vertical direction.

Recent imaging of the disc around the V4046$\,$Sgr spectroscopic binary revealed concentric regions of dust rings and gaps. The object's proximity and expected equilibrated state due to its old age (>20$\,$Myr) make it a superb testbed for hydrodynamical studies in direct comparison to observations. We employ two-dimensional hydrodynamical simulations of gas and multiple dust species to test whether the observed structure conforms with the presence of giant planets embedded in the disc. We then perform radiative transfer calculations of sky images, which we filter for the telescope response for comparison with near-infrared and millimetre observations. We find that the existing data are in excellent agreement with a flared disc and the presence of two giant planets, at 9$\,$au and 20$\,$au, respectively. The different ring widths are recovered by diffusion-balanced dust trapping within the gas pressure maxima. In our radiative transfer model, the diffusion in vertical direction is reduced in comparison to the radial value by a factor of five to recover the spectral energy distribution. Further, we report a previously unaddressed, azimuthally-confined intensity decrement on the bright inner ring in the near-infrared scattered light observation. Our model shows that this decrement can be explained by a shadow cast by a circumplanetary disc around the same giant planet that creates the inner cavity in the hydrodynamical simulations. We examine the shape of the intensity indentation and discuss the potential characterisation of a giant planet and its associated disc by its projected shadow in scattered light observations., 15 pages, 13 figures, accepted for publication in MNRAS

Since the first investment in mining operations is very high, so, it is absolutely important to model the field in three dimensions for appropriate planning and cost analysis. The whole data set belonging to the geological, geophysical and drilling exploration studies carried out in the field should be evaluated as a package. In the modelling phase, the computer-aided tri-dimensional mining software has been used instead of the classical reserve calculation methods being utilized in previous years. Thus, more realistic and shorter results are achieved. In the present work, three-dimensional seam modelling of the Adana-Tufanbeyli (Turkey) lignite field was carried out. In modelling, the coal horizon of the field was examined. Then, the sub-seam levels in the horizon were determined and after examining their geometric relationships with each other, three sub-seams were defined. Seam composites were prepared by the downhole method to make the analysis results of different sizes uniform. It is possible to make block quality estimations, which will be the basis for reserve calculations, by creating variograms in different directions. Variograms are first created in the vertical direction and then in the horizontal direction respectively, to obtain the necessary parameters. The nugget effect and structural distance parameters were obtained from the created variogram models. To assign quality estimation values on the block model, the Kriging method was used when the number of data was sufficient, and the inverse distance method was applied, when it was insufficient. As a result of this modelling study, a total of 355.617.194 tons of lignite reserves with an average calorific value of 1.153 Kcal/kg were determined in the field.

Due to the high height of the refinery flares, the wind velocity plays an important role in flame shape and the resulting temperature distribution in flare body. The investigation of wind velocity effect on flame pulldown (downwash) can provide effective solution to avoid the flame pulldown problem and burning the flare tip. In this study, using the three-dimensional numerical simulation of the combustion, the performance of the Khangiran gas refinery flares is evaluated as a case study. For this reason, the effect of wind velocity is studied on influential parameters such as combustion efficiency, temperature distribution, pollutant emissions and pulldown phenomenon. Results show that the wind velocity has significant effect on temperature distribution, air–fuel mixing and combustion efficiency since with increasing the wind velocity to more than 4 m/s, the flame axis is diverted from vertical direction and is oriented horizontally based on the wind velocity. In addition, by increasing the wind velocity from 4 m/s to its maximum value at Khangiran region (11 m/s), the combustion efficiency decreases by 5%.

Partially missing bands in the preset region for Hough transform might strongly affect the accuracy of indexing Kikuchi patterns and reduce the quality of electron backscatter diffraction (EBSD) maps. This paper proposes a novel local band detection method for such kind of low-quality patterns. The approach involves rotating bands to vertical direction, detecting the local line segments through calculating the largest horizontal average grey gradient with a constant interval of 400 pixels in vertical direction, and applying Hough transform as well as weighted averaging to these line clusters to unify the edges of Kikuchi band. Therefore, even if only part of a Kikuchi band is visible, the entire band can also be accurately extracted. The average interplanar angle error obtained by the proposed method is approximately 29.0% less than those obtained by Hough transform-based technique. Moreover, the comparison of mean angular deviation (MAD) is also discussed. The average MAD of this method is about 38.5% lower than that of Hough transform-based technique. Consequently, the local Kikuchi band detection method is expected to be used for post-processing and re-indexing the EBSD low-quality patterns.

The China Seismo-Electromagnetic Satellite (CSES) was successfully launched on February 2, 2018, with a plasma analyzer package (PAP) onboard to in-situ detect the ionospheric ion parameters. In this paper, the availability of PAP data is investigated for the first time through analyzing three typical ionospheric disturbance events. Firstly, the ionospheric radio and plasma disturbances caused by two high-power terrestrial very low frequency (VLF) transmitters over American NAA station and Australian NWC station are investigated. Furthermore, several possible anomaly observations before the 22 August 2018 Ms7.3 Venezuela earthquake are analyzed. In the southwest of the epicenter, the oxygen ion density increased significantly, and the ion drift velocity in vertical direction reversed synchronously from space-to-ground direction to ground-to-space direction. Finally, during a global intense geomagnetic storm event which started from August 25, 2018, the oxygen ion density well reflected the geomagnetic storm event’s temporal evolution process. The results show that the PAP onboard CSES has ability to discern the relative variations and features of ionospheric disturbances.

The current study performed the laboratory flume to examine the velocity distribution and the velocity moments of turbulent flow over a sand-gravel mixture bed. The 3D instantaneous velocity data of water is collected by using acoustic doppler velocimeter (ADV) at the test section which will provide an important data related to the flow turbulence. The parameters of turbulence measured that the lower value of longitudinal velocity (velocity along flow direction) is observed close to the bed surface and increases with the flow depth. The lower magnitude of von Karman constant is achived than the universal value. The damping of Reynolds shear stress observed close to the boundary wall indicating lower exchange of flow energy towards the boundary and vice versa. The sand-gravel bed influenced the turbulence intensities with higher magnitude in the streamwise than those in vertical direction. The velocity moments which shows the structure function of fluctuating components of velocity, has been analyzed. The present study also analysed the flow anisotropy, and the flatness factor in the flow.

In this study, a new alloy material Mg-Zn-Zr (ZK60) was designed for the connecting rod. It was found that the blanks sampled along the vertical direction of an extruded bar crack during the roll forging process. The microstructure and precipitates of the extruded bar were observed and analyzed using optical microscope (OM), scanning electron microscope (SEM) and x-ray diffraction (XRD). The result showed that the Zn, Zr, and MnZn2 precipitates were elongated along the extrusion direction. The mechanical anisotropy was investigated by testing the mechanical properties of the specimens sampling from different angles. Hot deformation behavior was further studied using the Gleeble 3500 thermal-mechanical simulator. The tensile and yield strengths were the highest along the extrusion direction, reaching 347 MPa and 301 MPa, respectively. The deformation resistance was also higher in the extrusion direction than that in the vertical direction. Fracture mechanisms of the sample from different directions were discussed. The ZK60 alloy was more susceptible to failure if the deformation direction was parallel to the bands of segregation area and precipitates.

Drill and blast is a commonly used method for rock slope excavation in hydropower engineering. During blasting excavation of rock slopes, far-field vibration monitoring on the first upper berm for statutory compliance is usually performed to control the blast-induced rock damage to the final slope face. In this study, for the rock slope excavation in the Jinping-I hydropower station, the field vibration monitoring and acoustic testing are presented to investigate the vibration characteristics on the first upper berm and the damage depth in the current bench. The relationship between the PPV on the first upper berm and the PPV damage threshold on the damage zone boundary is also studied through three-dimensional FEM simulations. The results show that on the first upper berm, the maximum vibration velocity component occurs in the vertical direction. While on the blasting damage zone boundary, the horizontal radial vibration velocity is the maximum component. For the Jinping-I slope with a bench height of 30 m, the radial PPV on the inner side of the first upper berm is 2.06% of the PPV threshold on the damage zone boundary. This ratio is increased as the bench height decreases. Therefore, the bench height of the rock slope is an important factor that cannot be ignored in determining the allowable vibration velocity for rock damage control.

Non-physiological sources may lead to equivocal interpretation on the degree of muscle excitation from electromyograms (EMGs) amplitude. This presumably explains the contradictory findings regarding the effect of the bench press inclination on the pectoralis major (PM) activation pattern. To contend with these issues, herein we used high-density surface EMG to investigate whether different PM regions are excited during the flat and 45° inclined bench press exercises. Single-differential EMGs were collected from 15 regions along the PM cranio-caudal axis, while 8 volunteers performed a set of the flat and 45° inclined bench press at 50% and 70% of 1 repetition maximum. The coefficient of variation, the range of motion, and the cycle duration were calculated from the barbell vertical position to assess the within-subject consistency across cycles. The number of channels detecting the largest EMGs amplitude (active channels), their interquartile range, and their barycentre coordinate were assessed to characterize the EMG amplitude distribution within PM. No significant differences in the range of motion (p > 0.11), cycle duration (p > 0.28), number of active channels (p > 0.05), and interquartile range of active channels (p > 0.39) were observed between the two bench press inclinations. Conversely, the barycentre shifted toward the PM clavicular region (p

Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory. The mechanical design of a beam-based alignment sextupole mover should be developed. The motion accuracy of the mover should be better than 5 μm under 450 kg load of sextupoles. The movement range is required to be ± 0.3 mm in both horizontal direction and vertical direction. And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz. The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness. And to find the difficulties of development of this mover. Interferometer is used to measure the motion accuracy, and pressure accelerometer is used to test the mover equivalent stiffness. Combining with the actual measurement results of equivalent stiffness, the natural frequency of the magnet support system is simulated. The motion accuracy reaches to 5.3 μm in vertical direction and 1 μm in horizontal direction, respectively. The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system. Unwanted movement coupling has occurred during the mover exercises in vertical direction. Through the research of experimental mover prototype, the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load. However, further researches and improvements are necessary to fix the coupling error during the vertical movement.

In a more electrified future, development of high power, compact, and synergistically cooled power electronics for improved performance and reliability is of critical importance to a broad range of defense and commercial applications. As power levels increase, power converters must manage higher thermal loads in smaller and lighter weight packages. This necessitates smarter packaging configurations and more aggressive cooling schemes. This work introduces a novel cooler design for thermal management of high-power switches in a dual active bridge converter: a vertically enhanced manifold microchannel system (VEMMS). As opposed to traditional flat heatsinks, this cooler shrinks in footprint but expands away from the board in the direction of its height ( $z$ -direction), for increased heat transfer area while keeping the footprint on the printed circuit board (PCB) at minimum. Since most power converters’ total height is dictated by magnetic elements such as the core, expanding the cooler in vertical direction does not reduce packing density, while it significantly enhances its thermal performance. Both liquid and air-cooled versions of the cooler are introduced through case studies, and their advantages are assessed through extensive numerical modeling. Volume based power densities of 20 kW/L for the overall converter and 286 kW/L for one full bridge assembly for a 10-kW power converter were attained.

This paper investigates a special atmospheric glide problem where the gliding speed is close to the first cosmic velocity (FCV). Here, the centrifugal force and gravity almost balance each other, and thus in the local vertical direction the lift force required to maintain the glide is almost zero. However, all the existing analytical solutions for 3-D gliding trajectories were derived under the condition that the vertical component of lift is large enough, and thus become invalid for the special glide case. To overcome the shortage of the existing studies, we abandon the vertical component of lift, but instead plan the profile of drag acceleration (aD) to derive the analytical solutions for the 3-D special gliding trajectory. By simplifying the nonlinear equations of motion properly, a reduced-order system is obtained and governed by aD and L2/D, where L2/D represents the ratio of the local horizontal component of lift to drag. Subsequently, by proposing a perturbation method to expand the system in Taylor series with finite terms, two analytically solvable subsystems are developed. As a result, the analytical trajectory solutions are obtained successfully. Additionally, as verified by the simulation results, the new solutions are also applicable to the conventional glide problem where the speed is much less than the FCV, and found to be much more accurate than the existing solutions because the new solutions give full consideration to the coupling of the longitudinal and lateral equations.

This study presents a method for measuring the imbalance in a small-sized cylindrical roller. The roller imbalance was calibrated on the built static-pressure-air flotation measurement machine. The impact of the roller imbalance on the dynamic characteristics of a cage were then studied on the aero-bearing test rig. The displacement spectrums with different roller imbalance of the obtained cage orbits under various bearing speed and radial load were used to evaluate the cage stability. The results show that the cage cannot form a stable operating state at a lower bearing speed with or without the unbalanced rollers. The cage with balanced rollers gradually develops stable motion with the increase of the bearing speed. The existence of a small roller imbalance causes the stability of the cage to deteriorate. With an increase in the bearing speed and radial load, the cage with the unbalanced rollers runs unsteadily accompanied by a high-frequency vibration when the roller imbalance is large enough. The vibration amplitude of the cage in the horizontal direction is greater than that in the vertical direction during an unstable operation, which is similar in the stable status.

A forward-view optical scanner made of a MEMS mirror typically needs a second mirror to fold the optical beam forward, and thus an assembly structure is required, which drastically increases the overall size and weight of the scanner. This paper reports an ultra-small forward-view optical scanner with two vertically oriented micromirrors integrated on a silicon optical bench (SiOB). A new latch structure is proposed to secure the mirror frame at its vertical position and an array of meander thin-film stripes is designed to assist the latching process. The new design has been successfully fabricated and shows much-improved verticality with a maximum deviation of less than ±2° from 90°. With an optical aperture of 0.7 mm, the form factor of the MEMS chip is 4.9 mm (length) by 4.7 mm (width) by 1.8 mm (height). The measured forward field of view (FoV) of the vertical micromirrors reaches 21° in both axes at non-resonance with the voltage amplitude less than 4 V. The first resonant frequency (corresponding to the mirror frame rotation mode) of the micromirror is about 630 Hz. A fiber-pigtail bonded forward scanner is assembled with a footprint of 2 cm by 1.2 cm and a weight of 0.6 g. A forward scanning LiDAR has been built with this new MEMS scanner. The non-resonant scanning capability enables forward-view adaptive resolution and zoom-in scanning capability. [2021-0132]

Even though high-strength steel has been widely used across the world, the global buckling behaviour of high-strength steel beams has yet to be systematically investigated through experimental tests and numerical simulations. This paper describes an experimental and numerical study of the lateral-torsional buckling resistance of welded Q690 steel beams. Eight beams with doubly-symmetric cross-sections and different height-to-width ratios were tested under a concentrated point load. To allow free lateral deflections, a special loading system was designed and erected at the mid-span of steel beams. The applied load remained in the vertical direction during the whole loading process, despite significant rotations and lateral deflections of the beam. The critical bending moment of steel beams was quantified in the experimental tests. Besides, numerical models were established by using ABAQUS and initial imperfections were properly defined in the model. Direct comparisons were made among numerical results of steel beams of different steel grades and design curves in different standards. Based on experimental and numerical results, recommendations were provided for the lateral-torsional buckling design of Q690 steel beams. It was suggested that GB50017-2003 and GB50017-201X can predict the buckling resistance of Q690 steel beams with slightly conservative results, Eurocode 3 yields rather conservative estimations, but ANSI/AISC360-10 significantly overestimates the buckling resistance.

To further develop a low-power, low-cost optical motion detector for use with traffic detection under dark and daylight conditions, we have developed and verified a procedure to use a near-sensor image processing programmable 2-D optical sensor in a “1-D mode” to achieve the effect of using a cylindrical lens, thus improving the angle-of-view (AOV), the sensitivity, and usefulness of the sensor. Using an existing $256\times 256$ element sensor in an innovative way, the AOV was increased from 0.4 $^{\circ }$ to 21.3 $^{\circ }$ in the vertical direction while also improving the sensitivity. The details of the sensor hardware architecture are described in detail and pseudo-code for programming the sensor is discussed. The results were used to demonstrate the extraction of local extreme points used for time-to-impact calculations to estimate the speed of an approaching vehicle.

Rubber is used as a vibration damper in many engineering applications, especially in the automotive industry. Rubber is used to dampen torsional vibration in internal combustion engines. Therefore, crank pulleys are used to dampen the crankshaft in a certain frequency range. Rubber durability is very important for the crank pulley to perform its duty for a long time. In this study, the dynamic life of NR45 natural rubber with two different mixtures used in crank pulleys was determined by the prepared test approach. A metal-rubber component structure used in the slip test samples was formed and produced. The metal-rubber component is left to force the rubber in the vertical direction with its natural frequency and specified amplitude to simulate torsional vibration in crank pulleys. A test setup design was carried out to force the metal-rubber component at the determined frequency. In the study, life expectancy estimates based on amplitude and frequency were created on experimental data.

The velocity required in IEC 61373 for long-life random vibration testing of Category-3 rolling stock equipment in the vertical direction is 2.7821 m/s, but the maximum velocity of existing electrodynamic shakers falls in the range of 2–2.5 m/s. In this study, an electrodynamic shaker with a velocity satisfying the requirements for vibration testing of Category-3 rolling stock equipment was developed. First, mechanical and equivalent circuit models of an electrodynamic shaker were developed. On this basis, reducing the impedance of the armature coil was identified as the best option for increasing the velocity of the shaker. However, owing to the impact of the back electromotive force of the armature coil, a decrease in the input impedance of the armature coil at low frequencies leads to an increase in its input impedance at high frequencies. To reduce the input impedance at high frequencies, a shading coil was incorporated into the circuit. The shading coil-incorporated new design was modeled using equivalent circuits and simulated numerically. The results showed that the improvement measures—incorporating a shading coil, increasing the cross-sectional area, and reducing the number of turns of the armature coil—effectively reduced the input impedance of the armature coil, thereby increasing the armature coil current and the velocity of the shaker. Finally, a shaker with a maximum velocity of 3.2 m/s was fabricated based on the new design and was validated to satisfy the high-velocity requirement for the long-life vibration test of Category-3 equipment in the vertical direction as specified in IEC 61373.

Flow-induced oscillation is an effective way to enhance heat transfer, which requires no extra energy consumption and can prevent fouling and soot formation. To test the flow-induced oscillation effect on the heat transfer of impingement flow, an 18 mm wide and 30 µm thick membrane tape was mounted at the exit of the ejection pipe. As the ejection Reynolds number increased from 5280 to 9827, the oscillating frequency also increased. In addition, three different oscillating regimes were observed, these being quasi-still, 2D-oscillating and 3D-oscillating, with the transition Re depending on the tape length. The heating plate was 3D-printed and electrical heating wires were embedded within it so as to predetermine the local heat flux by numerical analysis, and be able to calculate the heat transfer coefficient (HTC). The results demonstrate that heat transfer enhancement is more prominent in the vertical direction to the tape than in the parallel direction. Moreover, the distinctive heat transfer enhancement effect near the plate center becomes weaker as it goes toward the outside of the plate, and even turns negative with an increasing r/D. Using a longer piece of tape or having smaller intervals between the tape tip and plate was also shown to improve the heat transfer effect. The spontaneous oscillating disturbance method shows great promise for heat transfer regulation in impingement flow.

Research on the influence of thermal radiation of tree canopies to adjacent exterior walls has relevance to the selection of tree species and the spatial arrangement of trees for urban planning. In the last decade, there have been many studies on the influence of tree shadows on the thermal environment and energy consumption of buildings. However, there is a lack of research on how trees affect the thermal radiation of adjacent buildings, when they do not cast direct shadows on the walls. In view of this, a combination of experiment and simulation was used to explore the influence of spherical canopy on the intensity changes of net long-wave thermal radiation (TRDL) and net short-wave thermal radiation (TRDS) absorbed by the adjacent wall. Both measured and simulated results show that the tree canopy has a TRD (the sum of TRDL and TRDS) effect on the south wall of adjacent buildings in summer. The peak of TRD from the tree to the adjacent wall was obtained by ENVI-met under 27 scenarios. A functional relationship was further given between the peak TRD and the canopy diameter (DC), the minimum distance between wall and tree canopy (DW-T). Moreover, the influence of DC, DW-T and leaf area density (LAD) on TRD was discussed by simulation. Additionally, the TRD of canopy decays exponentially in the horizontal direction and linearly in the vertical direction of the wall. The above methods and results can guide the selection of tree species, green space design around buildings and the evaluation of the influence of trees on indoor cooling energy consumption in summer.

Shoaling internal solitary waves near the Dongsha Atoll in the South China Sea dissipate their energy and enhance diapycnal mixing, which have an important impact on the oceanic environment and primary productivity. The enhanced diapycnal mixing is patchy and instantaneous. Evaluating its spatiotemporal distribution requires comprehensive observation data. Fortunately, seismic oceanography meets the requirements, thanks to its high spatial resolution and large spatial coverage. In this paper, we studied three internal solitary waves in reversing polarity near the Dongsha Atoll and calculated their spatial distribution of diapycnal diffusivity. Our results show that the average diffusivities along three survey lines are 2 orders of magnitude larger than the open-ocean value. The average diffusivity in internal solitary waves with reversing polarity is 3 times that of the non-polarity reversal region. The diapycnal diffusivity is higher at the front of one internal solitary wave and gradually decreases from shallow to deep water in the vertical direction. Our results also indicate that (1) the enhanced diapycnal diffusivity is related to reflection seismic events, (2) convective instability and shear instability may both contribute to the enhanced diapycnal mixing in the polarity-reversing process, and (3) the difference between our results and Richardson-number-dependent turbulence parameterizations is about 2–3 orders of magnitude, but its vertical distribution is almost the same.

During long-distance excavation, a tunnel boring machine (TBM) encounters boulders that affect the safety and progress of construction. To ensure the smooth progress of tunnel construction, it is necessary to delineate their locations and ranges before construction. The large resistivity difference between boulders and the surrounding medium makes the electrical resistivity tomography method capable of boulder detection. This study established different spatial boulder distribution models and analyzed the advantages and disadvantages of cross-hole resistivity tomography and surface resistivity data for boulder detection. After that, we evaluated imaging features of resistivity data fusion of these two methods based on principal component analysis. The results indicated that (1) the cross-hole resistivity tomography imaging ability near the borehole can be improved. With the addition of valid data, the surface resistivity data improved the capacity to determine peripheral geological anomalies, especially at the interfaces. (2) The resolution of the surface resistivity data in the vertical direction and the cross-hole resistivity tomography in the lateral direction has also been improved, and the ability to identify single anomalies has been enhanced. As two-dimensional (2D) profiles may not accurately locate the boulders, we proposed a three-dimensional (3D) coordinate conversion method that unifies different data to the same coordinate system. We adopted interpolation to conduct 3D imaging, thus improving the intuitiveness of the detected results. The successful application of boulder detection in the shield section of the Dalian subway proved the rationality of the method. It provided corresponding guidance and guarantees for safety construction with the TBM.

In this study, a machine vision-based pattern matching technique was applied to estimate the location of an autonomous driving robot and perform 3D tunnel mapping in an underground mine environment. The autonomous driving robot continuously detects the wall of the tunnel in the horizontal direction using the light detection and ranging (LiDAR) sensor and performs pattern matching by recognizing the shape of the tunnel wall. The proposed method was designed to measure the heading of the robot by fusion with the inertial measurement units sensor according to the pattern matching accuracy; it is combined with the encoder sensor to estimate the location of the robot. In addition, when the robot is driving, the vertical direction of the underground mine is scanned through the vertical LiDAR sensor and stacked to create a 3D map of the underground mine. The performance of the proposed method was superior to that of previous studies; the mean absolute error achieved was 0.08 m for the X-Y axes. A root mean square error of 0.05 m2 was achieved by comparing the tunnel section maps that were created by the autonomous driving robot to those of manual surveying.

Inkjet printing technique is susceptible to form coffer-ring patterns and inhomogeneous films owing to the evaporation and its accompanying hydrodynamics of microscale quantum dot droplet. Pioneer efforts are usually confined to two-dimensional flat substrates and inks with mixed solvents/additives. Herein we demonstrate that physically confined space offers an additional parameter in tailoring such processes of droplets and the following quantum-dot self-assembly deposition, without extra modification of quantum dots or solvent chemistry. Owing to the boundary of physically confined space, two three-phase border lines in both the bottom center (horizontal direction) and the barrier of the bank substrate (vertical direction) arise, inducing dual capillary flows and Marangoni backflows. The evaporation, fluid flow, and film-forming process in physically confined space are studied by introducing well-prepared single-solvent quantum dots inks. The systematical analysis offers valuable instructions including ink preparation, surface modification, and postprocessing evaporation technique for inkjet-printed patterning applications, especially for pixelated display, polychrome patterning, and sensor array.

The purpose of this study was to investigate the association between the vertical position of the central retinal vessel (CRV) within the optic nerve head (ONH) and the site of visual field defects (VFDs) in glaucoma.Cross-sectional study.The vertical position of the CRV was identified in 134 glaucoma eyes and 61 normal eyes at the point at which CRV exited the lamina cribrosa (LC) onto the ONH surface, by using spectral-domain optical coherence tomography (exit position). The position was also identified at the entry point into the LC from the retrolaminar ONH region (entry position), which was little influenced by glaucomatous LC deformation, therefore close to the original position before the glaucoma development. Positions were compared among glaucoma eyes with different sites of VFDs, and between glaucoma and normal eyes.In glaucoma eyes, the entry position of the CRV was in the superior ONH region in 63.0% of eyes with superior VFDs and in the inferior ONH region in 97.8% of eyes with inferior VFDs (P.0001). The exit position exhibited a similar percentage. The vertical CRV positions were not significantly different between glaucoma and normal eyes, both at the entry and exit positions.Eyes with CRVs in the superior ONH region were significantly more likely to form VFDs in the superior hemifields and vice versa. The vertical position of the CRV was little altered by the development of glaucoma. The original position of the CRV before the development of glaucoma may influence regional susceptibility to glaucomatous stress and may be useful in predicting initial sites of VFDs.

Photovoltaic performance is significantly affected by soiling on its covering surface, which is strongly influenced by its tilt angle. This raises concern for the potential investor, policymakers, engineers, and local populace in regions where the soiling rate and its potential threats remain relatively unexplored. This study investigated the effect of dust accumulation on PV, considering the influence of tilt angle using a low-cost in-house developed soiling station exposed in a region with high solar energy potential, low PV penetration and high energy demand. Low iron glass coupons were exposed monthly, seasonally, and annually, each in three-position (horizontal, 45° tilt, and vertical plane). The result revealed that the highest reduction in transmittance was recorded on a horizontally positioned coupon with a significant decrease of about 88%. In comparison, the lowest transmittance reduction of an exposed coupon was recorded from a vertical position with about a 1% reduction. These transmittance reductions were further illustrated using PV power output reduction. Accumulated dust density on each coupon was recorded, with the lowest of about 0.2 g/m2 and the highest of 12.56 g/m2. It was concluded that horizontally positioned coupons accumulated more dust and gradually decreased as the angle tilted towards the vertical position. This research work highlights cycles of high soiling in the region; the information could be used to predict soiling events that could provide maintenance guidance where optimum scheduling for preventing and restoring PV performance can be achieved.

A thin-film deposition system was developed for the surface coating of X-ray mirrors of up to 1 m in length. With two coating process areas and four sputtering cathodes, various combinations employing a single layer, multilayered, and co-sputtered thin films are possible. Furthermore, it is possible to correct and modify the mirror surface shape by controlling the speed of the substrate stage. In this study, to evaluate the performance of the proposed coating system, the static coating distribution was measured to check the vertical direction. In a 10 mm area, a 0.9% peak-to-valley error and 0.2% root mean square error occurred. A differential deposition test was also performed for the horizontal direction (stage scan direction). In this study, arbitrary shapes were deposited on 100-mm and 400-mm-long mirrors. After removing the measurement error, the deposition error was less than 1 nm (peak-to-valley). The results demonstrate that this system can correct the surface of an X-ray mirror with ultra-high precision.

In this study, the suspension stability of a maglev vehicle is investigated under steady aerodynamic load. The dynamics of the maglev vehicle in the vertical direction are modelled by considering aerodynamic lift and pitching moment, and this model is adopted to investigate how the aerodynamic load influences the suspension stability by analysing the critical speed by means of eigenvalue analysis and direct integration. Doing so reveals three modes of suspension failure: (i) an upward aerodynamic load or pitching moment can give rise to a dynamic instability, (ii) a downward aerodynamic load can give rise to a static instability and (iii) the electromagnet becomes locked in the guide-way because the vertical aerodynamic force borne by the electromagnet exceeds the vehicle weight borne by it, and the electromagnetic force cannot adjust the suspension gap. In essence, failure modes (i) and (ii) correspond to motion stability when the maglev vehicle system is perturbed by a small amount, whereas failure mode (iii) is similar to the electromagnet holding the track in the event of control failure, albeit by a different mechanism. Each suspension failure mode has its own critical speed, and how that speed depends on the aerodynamic coefficients and feedback control gains is determined.

With the rapid demand for high-performance and power-efficient memristive and synaptic systems, more 2D heterostructures with improved resistance switching (RS) properties are still urgently in need for next-generation devices. Here, we report the RS behaviors of vertical MoOx/Mo2C heterostructures fabricated by controllable thermal oxidation and uncover the failure behavior for the first time. It is found that the MoOx/Mo2C heterostructure exhibits bipolar RS with a low set/reset voltage of +0.5/-0.3 V, an ultralow power consumption of 5 × 10-8 W, and an on/off ratio of 102, which is ascribed to the transport of the internal oxygen ions of MoOx. Furthermore, the failure behavior of RS behaviors of the MoOx/Mo2C heterostructure under a higher work voltage is revealed. It indicates that the amorphization of the pristine crystalline MoOx layer could block the movement of the internal oxygen ions in the vertical direction. The excellent RS performance induced by the synergy of MoOx and Mo2C and the demonstration of the failure behavior enable the potential applications of the 2D heterostructure in related memory devices and biological neural networks.

This work presents an in-situ technique to quantify the layer-by-layer roughness of thin films and heterostructures by measuring the spectral profile of the reflection high-energy electron diffraction (RHEED). The characteristic features of the diffraction spot, including the vertical to lateral size ratio c/b and the asymmetrical ratio c1/c2 along the vertical direction, are found to be quantitatively dependent on the surface roughness. The quantitative relationships between them are established and discussed for different incident angles of high-energy electrons. As an example, the surface roughnesses of LaCoO3 films grown at different temperatures are obtained using such an in-situ technique, which are confirmed by the ex-situ atomic force microscopy. Moreover, the in-situ measured layer-by-layer roughness oscillations of two LaCoO3 films are demonstrated, revealing drastically different information from the intensity oscillations. The experiments assisted with the in-situ technique demonstrate an outstanding high resolution down to ∼ 0.1 A. Therefore, the new quantitative RHEED technique with real-time feedbacks significantly escalates the thin film synthesis efficiency, especially for achieving atomically smooth surfaces and interfaces. It opens up new prospects for future generations of thin film growth, such as the artificial intelligence-assisted thin film growth.