Cross Configurations Research Articles

Evaluation of the Respective Effects of Microphone Type and Dummy Head Type on Measured Head-Related Transfer Functions

A dummy head is a tool used to generate binaural recordings, i.e. recordings when listened to through headphones that allow for the listener to hear from the dummy's perspective. A dummy head typically includes pinnae and ear canals in which microphones are placed. The global shape of a dummy head replicates an average-sized human head, and variations around this average will depend on the manufacturer (pinnae of different size, presence of a nose or a mouth). This paper describes measurements conducted on two dummy heads in order to evaluate and rank the respective influence of microphone type and dummy head shape on spatialization cues. Four possible cross configurations are tested, that is head 1 or 2 with microphones pair 1 or 2. For each configuration, head-related transfer functions are measured in an anechoic room for various azimuth and elevation angles. The results obtained show that the effect of the dummy head shape is larger than the effect of the microphone type on measured head-related transfer functions. A practical implication of this result is found when microphones have to be replaced on a given dummy head.

Multibeam sonar water column data simulation for improved and automated detection of gas seeps

Water column data (WCD) collected by multibeam echosounders (MBES) provide valuable datasets for the detection of gas bubbles. However, the presence of noise patterns, primarily caused by sidelobe interference from seafloor reverberation, limits the usability of WCD. We present a method for simulating characteristic noise patterns in WCD, particularly in Mills Cross configurations, by simulating predicted seafloor reverberation and transducer artefacts. The simulation is based on a reference pattern created from a subset of data and then applied as a correction based on the depth and seafloor backscatter of each ping within the dataset. Noise patterns can be removed by subtracting the simulated data from the original data, allowing for improved analysis of near-benthic water column features such as gas seeps. This method requires no prior knowledge of specific transducer characteristics, making it applicable to a wide range of MBES systems and acoustic targets. This method was applied to two MBES datasets collected simultaneously over a seep field in the Bay of Plenty, New Zealand, as part of the Quantitative Ocean-Column Imaging (QUOI) voyage in July 2018. We demonstrate the utility of applying a reference pattern for detecting the spatial extent of gas seep bases mapped using two different frequencies.

Microstructure features of transformed α induced by β texture in electron beam welded joint of TC25G titanium alloy

The microstructure morphology of transformed α is controlled by the crystallographic orientation of its parent β grain. In the fusion zone of an electron beam welded joint of TC25G titanium alloy, the columnar β grains exhibited a {001} 〈100〉 cube texture, in which four kinds of α laths with two main growth (trace line) directions formed after post-welded heat treatment. According to the numerical simulation by an orientation-trace method, the trace angle of α laths mainly distributed across the ranges of 40˚-60˚ and 120˚-140˚ in the β matrix with 〈001〉 fiber texture, thus the microstructure morphology of transformed α naturally tended to form cross configurations with two nearly perpendicular α laths.

Simulating a Hybrid Acquisition System for UAV Platforms

Currently, there is a rapid trend in the production of airborne sensors consisting of multi-view cameras or hybrid sensors, i.e., a LiDAR scanner coupled with one or multiple cameras to enrich the data acquisition in terms of colors, texture, completeness of coverage, accuracy, etc. However, the current UAV hybrid systems are mainly equipped with a single camera that will not be sufficient to view the facades of buildings or other complex objects without having double flight paths with a defined oblique angle. This entails extensive flight planning, acquisition duration, extra costs, and data handling. In this paper, a multi-view camera system which is similar to the conventional Maltese cross configurations used in the standard aerial oblique camera systems is simulated. This proposed camera system is integrated with a multi-beam LiDAR to build an efficient UAV hybrid system. To design the low-cost UAV hybrid system, two types of cameras are investigated and proposed, namely the MAPIR Survey and the SenseFly SODA, integrated with a multi-beam digital Ouster OS1-32 LiDAR sensor. Two simulated UAV flight experiments are created with a dedicated methodology and processed with photogrammetric methods. The results show that with a flight speed of 5 m/s and an image overlap of 80/80, an average density of up to 1500 pts/m2 can be achieved with adequate facade coverage in one-pass flight strips.

Influence of Volume Withdrawal of High-Rise Buildings on the Visibility of Sky View Factor and Urban Microclimate

隨著全球都市高度開發並朝向高層高密度化發展，土地使用方式不斷改變，建築型態逐漸朝向高層、高密度化，導致都市溫度不斷上升，影響人體舒適度與生活品質。據研究指出透過建築量體退縮設計，有助於提升都市通風與形塑良好的天空視野與都市環境，進而改善熱島效應並提升環境舒適度。本研究針對台北市高層高密度化之連棟型、雙拼型以及風車十字型等三種建築配置進行都市微氣候分析，比較不同住宅配置形式及天空可視率之量體退縮尺度，同時探討量體退縮尺度與SVF之關係，分析道路寬度（W）、退縮高度（H）、退縮深度（D）與SVF對都市微氣候之影響。結果顯示，透過概念城市模擬方案可得知為改善行人尺度微氣候環境應以底層退縮進行設計，而欲改善都市冠層微氣候環境則應以頂層退縮進行設計。更新改善方案整體以迎風側較背風側之街區建築量體退縮設計更有效改善行人尺度微氣候；不同配置形式量體退縮改善方案影響舒適度效果為風車十字型＞雙拼型＞連棟型配置，且整體以風車十字型配置之底層退縮12m設計為天空可視率及舒適度最佳方案。With the development of high-rise and high-density cities around the world, the land use pattern is changing, and the building pattern is gradually moving towards high-rise and high-density, which leads to the rising of urban temperature and affects human comfort and quality of life. In this study, the national residences of different configurations in the capital city of Taiwan-Taipei are taken as the research object, and three high-rise high-density areas, such as the Townhouse type (Zhongxiao commercial circle-Guangwu new village), the Duplex type (Shida commercial district-Taishun public housing),and the Cruciform type (Minsheng community-Pine Hill new village), using the field measurement and computational fluid dynamics software as the analysis tool, the overall micro-climate simulation analysis was performed using the data obtained from the TETO 480 multi-function environmental measuring instrument and the Sky View Factor (SVF), by comparing the volumetric retreat scale of different housing configurations and sky visibility, and exploring the relationship between volumetric retreat scale and SVF, the effects of road width (W), retraction height (H), retraction depth (D) and SVF on urban microclimate were analyzed. The results show that both the type and scale of housing configuration had an influence on the SVF and the comfort degree of the environment. The best microclimate environment is the windmill cross configuration, and the SVF index is higher with the depth of retreat Through the conceptual urban simulation scheme, it can be concluded that the design for improving the pedestrian microclimate environment should be based on the base retreat, while that for improving the urban canopy microclimate environment should be based on the top retreat. As a whole, the pedestrian-scale microclimate can be improved more effectively by the retrogression design of the building volume on the upwind side than on the leeward side. The effect of different configurations on the comfort is as follows: The Windmill Cross, double mosaic, and multi-span configurations. The overall design of 12m in the bottom of the Windmill Cross is the best one for the visibility and comfort of the sky.

Design, manufacturing, and performance evaluation of a novel smart roller bearing equipped with shape memory alloy wires

In this study, a new type of seismic isolation device, called shape memory alloy (SMA) wire-based roller bearing (SMA-RB) is developed and introduced. The SMA-RB has been designed, manufactured, and experimentally tested. This bearing consists of cylindrical roller bearings and SMA wires with straight or cross configurations, as supplementary damping elements. In such a smart bearing, the superelastic (SE) SMA wires are passed through the hooks/pulleys attached to the supporting plates of the bearings in different configurations. The rollers provide lateral flexibility, and SMA wires supply energy dissipation and self-centering (SC) properties. In the manufacturing stage, a new mechanism for coupling wires (i.e. SMA wire joiner/coupler) is proposed. The results show that SMA wires, made of nickle titanium (NiTi), provide a SC damping mechanism with almost zero residual deformation which can effectively control the device from over-displacement. While using pulleys and newly designed wire joiners in the SMA-RB, the bearing can experience a stable cyclic behavior. Since the rollers generate a negligible amount of frictional force, the SE NiTi wires with a flag-shaped hysteresis mainly contribute to the overall shear hysteretic response of the SMA-RB. A triangular-shaped constitutive model can be used to accurately describe the hysteretic behavior of SMA-RB with different wire configurations.

Poređenje dinamičkog modela i kontrole leta plus i unakrsnih kvadkopter konfiguracija

This research investigates and demonstrates the fundamental differences in performance and operation of both the cross and quadcopter configurations. The system's nonlinear dynamic model was first derived and implemented in Simulink for each quadcopter. The identical initial control values were applied for both quadcopters. The plus-configuration creates a yaw moment when a pitch or roll control input is supplied using multi-rotor controls; however, the cross-configuration decouples pitch and roll control from yaw. However, the plus-quad showed considerable instability while rotating with a pitch and rolling due to the self-generated residual rotation of the four rotors, which is small in the cross quadcopter, making it more maneuverability stable. The obtained results showed that both quadcopters consume the same energy amount.

Seismic vulnerability assessment of elevated water tanks with variable staging pattern incorporating the fluid-structure interaction

The damage suffered by elevated water tanks in previous seismic events can be generally attributed to poor performance of their frame-type supporting structure. It is pivotal to quantify the damage experienced by these tanks in damage states in order to ascertain their performance. In this study, the nonlinear response of frame-supported elevated water tanks is investigated using performance-based earthquake engineering method by utilizing the top drift of frame staging as the engineering demand parameter to evaluate its performance level. The influence of different patterns of reinforced concrete frame staging on the response of elevated water tanks was quantified using a fragility assessment. Finite element approach was employed and a total of nine models were developed representing the variation in staging patterns (basic, cross, and radial bracing configurations) and water-filling levels (empty, half-full, and full conditions) of the tanks and considering the fluid–structure interaction effect. Non-linear analyses were performed based on different seismic scenarios, and the seismic damage states from each staging pattern were evaluated. Fragility curves were generated according to three performance limit states specified in Vision 2000 and based on incremental dynamic analysis results for each staging pattern. Finally, the collapse margin ratios were quantified to evaluate the seismic safety margin against collapse of the elevated water tanks. From the analysis results, elevated water tanks having staging with cross and radial configurations showed better seismic performance compared to the basic configuration.

A novel understanding of circular four-coil configuration for uniform magnetic field generation

The uniform magnetic field is widely used in sensors and other laboratory devices. The four-coil configuration has the advantage of open space and good uniformity. Traditional schemes include Lee-Whiting, Tetracoil, Braunbeck, etc. The first two schemes have rounding errors of coil turns. The Braunbeck configuration avoids rounding errors, but the structure is solidified and cannot meet the requirements of flexible sensors. In this study, we derive a general constraint equation that fits various four-coil configurations and show that the constraint parameter uniquely defines the configuration. Moreover, we develop a simple optimization approach that allows building the optimized configuration that lacks rounding errors of coil turns. We analyzed system performance for different coil cross sections and configurations. The comparison of the original Lee-Whiting and optimized coils revealed that the normalized maximum radius Rmax increased by 7.67%. Finally, the increase in cross-section resulted in performance that was principally different from classical models. The proposed approach makes both scientific and educational contributions for future studies.

Polarized Raman Spectra and Complex Raman Tensors of Antiferromagnetic Semiconductor CrPS4

Chromium thiophosphate (CrPS4), a monoclinic crystal of C_2^3 space group, is a ternary layered semiconductor with an optical bandgap of 1.4 eV and exhibits antiferromagnetism below 36 K. Despite its potential in optoelectronic and magnetic applications, the symmetry of its lattice vibrations has not been systematically studied. In this work, we performed a polarized Raman spectroscopy of bulk CrPS4 using three different excitation wavelengths of 457, 514, and 633 nm. High-quality crystals grown by the chemical vapor transport method were mechanically exfoliated or polished to expose three orthogonal crystallographic facets. Polarized Raman spectra were obtained in parallel and cross configurations by rotating samples about the surface normal to each of the facets. Among 33 Raman active modes (16 A and 17 B) at the Brillouin zone center, 19 (8) peaks observed in the parallel (cross) configuration were assigned as A (B) modes. Complex-valued Raman tensors were determined for 7 major A modes using the angle-dependent Raman spectra of the three facets. The results can also be used in determining the crystallographic orientations of CrPS4 unequivocally.

Single-molecule conductance in a unique cross-conjugated tetra(aminoaryl)ethene.

A 1,1,2,2-tetrakis(4-aminophenyl)ethene with three paths of π-conjugation, linear-cis, linear-trans and a cross-conjugation, has been prepared. The molecule is able to bind to gold electrodes forming molecular junctions for single-molecule conductance measurements. Only two regimes of conduction are found experimentally. The modelling of the conductance allows to assign them to through-bond transmission in the linear case, while the cross-conjugated channel is further assisted by through-space transmission, partially alleviating the destructive quantum interference.

“DOUBLE X” FIXATION FOR RARE AND PARTICULAR PEDIATRIC SUPRACONDYLAR HUMERUS FRACTURES

Background Context. The presence of special, rare and various forms which we can encounter when treating supracondylar humeral fractures (SHF) in children, call into question what therapeutic methods can be used to increase the effectiveness of the treatment applied. The aim of this paper is to present the results obtained by using double cross-fixation, "in double X", by closed reduction and percutaneous pinning (CRPP) or open reduction and internal fixation (ORIF) in treating rare and particular forms. Comments and opinions on "double X" method and other cross or side configurations are presented. Patient Sample. All patients with rare and particular forms presented in this article, were operated during 2001-2020 in state and private hospitals. Fixation in "double X" was used either by CRPP and ORIF. The epitrochlear approach (EA) was performed in cases where stability by CRPP could not be ensured or when there were clear signs of ulnar nerve damage. The minimal medial-approach (mMA) highlights the epitrochlea and the fracture of the medial pylon; it has the role of anatomically reducing the medial pylon, thinner and very unstable in rare and particular forms. During 1982-2020 we consulted, treated and evaluated patients with SHF to whom all known treatment methods were applied: orthopedic reduction and immobilization in plaster cast, CRPP, ORIF, minimal-open reduction and internal fixation (mORIF) by mMA and external fixator. Internal fixation was done by the techniques of Judet, San Antonio, San Diego, Dorgan, in “X” and “double X”. In 2001, I introduced "double X" fixation to better stabilize anatomical reductions that showed signs of instability during intraoperative verification. All indications given in the study protocol have been made in accordance with the regulations mentioned in the experimental program. Results. All SHFs operated by CRPP and ORIF by “double X” were cured and satisfactory and good results were obtained in the neglected types operated between 14 and 60 days and good and excellent results were obtained in the rare forms. Conclusions. “Double X” fixation gives the best stabilization and postoperatively there is no need for immobilization in a plaster cast. Recovery may begin the day after surgery. Keywords: supracondylar fractures, child elbow pathology, cross-fixation, lateral fixation, healing and recovery after 30-45 days.

Wake symmetrization of a bluff Ahmed body based on sliding mode control

Aerodynamic drag reduction is needed to develop future fuel efficient ground transportation vehicles. Our study targets bluff bodies with wake asymmetries due to natural bistability or cross wind contributing to the drag increase at high velocities. The originality of this work is to apply closed loop control techniques based on sliding mode control theory and a Smith like predictor scheme for delay compensation in order to force the wake symmetry. This non linear controller was tuned thanks to experimental study of pulsed jet actuators placed at the back of a modified Ahmed bluff body and shows that wake symmetrization can be achieved either in aligned or cross wind configurations.

Comparative study of the conventional types of heat and mass exchangers to achieve the best design of dew point evaporative coolers at diverse climatic conditions

The objective of this research is a comparative analysis of various kinds of heat and mass exchangers of dew point indirect evaporative cooler. Considering three key performance parameters of an evaporative cooler, namely life-cycle cost, annual water consumption and the annual average of the coefficient of performance as objective functions, the best design of two popular types of the dew-point evaporative cooler (counter-regenerative and cross configurations) for employing in small-scale residential buildings was found through a multi-objective optimization approach. Both operational and geometric characteristics of the coolers were selected as the design (decision) variables while proper constraints such as thermal comfort were imposed. Afterward, between the optimized counter-regenerative and cross configurations, the foremost one was selected for representative cities of four diverse groups within the Köppen-Geiger climate classification system. It was found that in very hot and dry areas, the counter-regenerative configuration was the ideal choice while in other investigated climates, using cross configuration was a better alternative. Moreover, the results showed that in comparison to the base case conditions by using the best-optimized configurations, 64.4, 86.4, and 1039.0% improvements in life-cycle cost, the annual water consumption, and the annual average of the coefficient of performance were achieved, respectively.

Multirotor Controls, Trim, and Autonomous Flight Dynamics of Plus- and Cross-Quadcopters

This paper examines a quadcopter operating in the plus and cross configurations. The plus configuration generates a yaw moment when a pitch/roll control input is introduced; but, for the cross configuration, the pitch/roll control is decoupled from yaw. Although the collective revolutions-per-minute control requirement, pitch attitude, and power requirement versus flight speed are identical for both configurations, in forward flight, the plus configuration requires a larger pitch control input because it uses only two rotors and a compensatory yaw control input. Quadcopters display two oscillatory modes in hover, a longitudinal phugoid mode (coupling longitudinal translation and pitch), and a lateral phugoid mode (coupling lateral translation and roll). Both modes are stable, and their poles are coincident in hover. In forward flight, the modes are distinct, and the frequency and damping of both modes increase. The nature of the lateral phugoid mode in forward flight is very similar to hover, but the longitudinal phugoid mode now includes altitude change. Over a certain airspeed range, a couple of real poles combine to produce an oscillatory short-period mode. No significant difference is seen in the autonomous flight dynamic characteristics between the plus and cross configurations. Maximum pitching and rolling moments produced by the cross configuration are greater than those produced by the plus configuration because all four rotors are used.

Finite Element Analysis of FRP Strengthened Masonry Walls Subject to In-Plane Loading

Interest in the application of Fiber Reinforced Polymer (FRP) for strengthening of masonry buildings has been growing steadily due to their ease of application and favorable structural at tributes. Some of these structural attributes include high ductility, stiffness, corrosion resistance and low weight. Studies have shown that FRP composites can improve the lateral resistance of un- reinforced masonry (URM) walls significantly. Analytical models and numerical calculations using finite element models developed for both cross and grid configurations of FRP strengthening are discussed in this paper. Different FRP strips are applied along the wall diagonals in the form of “X” shape and vertically and horizontally along the wall on one side. The walls were subjected to in-plane loading. Results showed that the application of FRP strips modified the static behavior of the walls due to transfer of tensile stresses from masonry to the FRP strips.

Magnification relations of quad lenses and applications on Einstein crosses

In this work, we mainly study the magnification relations of quad lens models for cusp, fold and cross configurations. By dividing and ray-tracing in different image regions, we numerically derive the positions and magnifications of the four images for a point source lying inside of the astroid caustic. Then, based on the magnifications, we calculate the signed cusp and fold relations for the singular isothermal elliptical lenses. The signed fold relation map has positive and negative regions, and the positive region is usually larger than the negative region as has been confirmed before. It can also explain that for many observed fold image pairs, the fluxes of the Fermat minimum images are apt to be larger than those of the saddle images. We define a new quantity cross relation which describes the magnification discrepancy between two minimum images and two saddle images. Distance ratio is also defined as the ratio of the distance of two saddle images to that of two minimum images. We calculate the cross relations and distance ratios for nine observed Einstein crosses. In theory, for most of the quad lens models, the cross relations decrease as the distance ratios increase. In observation, the cross relations of the nine samples do not agree with the quad lens models very well, nevertheless, the cross relations of the nine samples do not give obvious evidence for anomalous flux ratio as the cusp and fold types do. Then, we discuss several reasons for the disagreement, and expect good consistencies for more precise observations and better lens models in the future.

Effects of reinforcement configuration and densification on impact strength of wood veneer/polyester composites

Current energy absorbers in industrial applications are made of metals or fiber-reinforced polymers using glass and carbon fibers. These materials are extremely stiff and strong but exhibit low-energy absorption when subject to the impact load. Other issues in the use of these materials are their high cost (fiber-reinforced polymer) and weight (metal). Wood reinforcements on the other hand are light weight and economic but less stiff. This study investigated the impact resistance and fracture patterns of wood-reinforced polyester composites using a drop-weigh impact test and considers the potential of using wood as a natural reinforcement in the manufacturing of polymer composites. Densified and un-densified Douglas-fir veneers were used to create three different mat configurations: woven, cross, and unwoven (unidirectional) mats. A total of 350 specimens were tested following ASTM D5420, and their impact resistance was calculated using the staircase method. Scanning electron microscopy was used to examine the resin distribution and its penetration into the reinforcement. Additionally, light micrographs of the veneers before and after densification were examined to determine the effect of densification on the cell-wall structure. Glass fiber-reinforced polymer samples had significantly higher impact resistance than the wood composites. Densification of the veneer did not significantly improve the composite performance. The effect of reinforcement configuration on the final performance of the wood–polyester composites, however, was significant with the woven, and cross configurations having notably higher impact energy than unidirectional composites.

Computational Fluid Dynamics Evaluation of the Cross-Limb Stent Graft Configuration for Endovascular Aneurysm Repair

The technique of crossing the limbs of bifurcated modular stent grafts for endovascular aneurysm repair (EVAR) is often employed in the face of splayed aortic bifurcations to facilitate cannulation and prevent device kinking. However, little has been reported about the implications of cross-limb EVAR, especially in comparison to conventional EVAR. Previous computational fluid dynamics studies of conventional EVAR grafts have mostly utilized simplified planar stent graft geometries. We herein examined the differences between conventional and cross-limb EVAR by comparing their hemodynamic flow fields (i.e., in the "direct" and "cross" configurations, respectively). We also added a "planar" configuration, which is commonly found in the literature, to identify how well this configuration compares to out-of-plane stent graft configurations from a hemodynamic perspective. A representative patient's cross-limb stent graft geometry was segmented using computed tomography imaging in Mimics software. The cross-limb graft geometry was used to build its direct and planar counterparts in SolidWorks. Physiologic velocity and mass flow boundary conditions and blood properties were implemented for steady-state and pulsatile transient simulations in ANSYS CFX. Displacement forces, wall shear stress (WSS), and oscillatory shear index (OSI) were all comparable between the direct and cross configurations, whereas the planar geometry yielded very different predictions of hemodynamics compared to the out-of-plane stent graft configurations, particularly for displacement forces. This single-patient study suggests that the short-term hemodynamics involved in crossing the limbs is as safe as conventional EVAR. Higher helicity and improved WSS distribution of the cross-limb configuration suggest improved flow-related thrombosis resistance in the short term. However, there may be long-term fatigue implications to stent graft use in the cross configuration when compared to the direct configuration.

Study on Two-Dimensional Sparse MIMO UWB Arrays for High Resolution Near-Field Imaging

A novel generic topology for two-dimensional (2-D) sparse multiple-input-multiple-output (MIMO) ultrawideband (UWB) arrays is suggested. Based on the proposed topology, a 2-D MIMO UWB array for high-resolution short-range imaging is developed. The focusing properties of this array are studied both theoretically and experimentally and are shown to be superior to those of arrays with a similar number of antennas and based on known topologies such as Mills Cross, rectangular, and spiral configurations. Decisive impact of a large operational bandwidth and short focusing distance on MIMO array performance is shown. Imaging capabilities of the proposed array are experimentally demonstrated for distributed targets.