Blind Zone Research Articles

A novel fault section locating method based on distance matching degree in distribution network

Fault section location of a single-phase grounding fault is affected by the neutral grounding mode of the system, transition resistance, and the blind zone. A fault section locating method based on an amplitude feature and an intelligent distance algorithm is proposed to eliminate the influence of the above factors. By analyzing and comparing the amplitude characteristics of the zero-sequence current transient components at both ends of the healthy section and the faulty section, a distance algorithm with strong abnormal data immune capability is introduced in this paper. The matching degree of the amplitude characteristics at both ends of the feeder section are used as the criterion and by comparing with the set threshold, the faulty section is effectively determined. Finally, simulations using Matlab/Simulink and PSCAD/EMTDC show that the proposed section locating method can locate the faulty section accurately, and is not affected by grounding mode, grounding resistance, or the blind zone.

Optimization of placement of piezoelectric wafers based on a hybrid model using pitch-catch and pulse-echo configurations

The development of Structural Health Monitoring (SHM) systems and integration in our structures is a necessity. It has proven to provide a robust and low-cost solution for monitoring structural integrity and can predict the remaining life of our structures. One of the most important aspects of SHM systems is the design and implementation of sensor networks. This study proposes a new hybrid model for optimizing sensor placement on convex and non-convex structures. We propose a novel framework in which two detection mechanisms are considered: pitch-catch and pulse-echo to provide coverage for a given surface. These two mechanisms will complement each other to minimize the number of sensors used while maintaining a high coverage. This combination also allows for better coverage of the corners and regions in the proximity of geometrical discontinuity (such as holes and openings). The monitored area is discretized into a set of control points. For a control point to be covered, it should satisfy the user-defined coverage level which is the number of sensing paths crossing that point. These sensing paths are provided by two modes of communications (pitch-catch and pulse-echo) between the actuator-sensor pairs. The model, which is solved using a genetic algorithm (GA), provides flexibility by allowing the user to input different parameters such as the attenuation distance of the propagating waves and the sensing path limits of both coverage configurations that can be determined through experimentation. The efficiency of the proposed model is then demonstrated by simulating different geometrical shapes. Significant improvement in the coverage of the monitored area, reaching 34.6%, was achieved when compared to the coverage provided by some preliminary solutions such as uniformly placing the sensors on the plate under study. Also, the advantage of combining both configurations (pitch-catch and pulse-echo) in the same model was investigated. It was shown that the latter highly impacted the coverage in the blind zones (corners and edges) where a single configuration is not effective. Afterward, experimental validation was carried out to evaluate the model’s accuracy in damage localization within the optimized sensor networks. The results demonstrated the proficiency of the model developed in distributing the sensors on the tested specimens.

Design and implementation of microstrip array antenna for intelligent transportation systems application

Abstract This article proposes a design and implementation of array Microstrip Patch antenna of configuration 2 × 2 at an operating frequency of 3.5 GHz. The proposed design takes a dimension of 80 mm × 92 mm × 1.6 mm with four radiating elements arranged in rectangular form with an optimized separation between the patches. All the radiating elements were connected through a corporate series network with an inset feed to have better impedance matching. The model gives an efficiency of 90.99% with a bandwidth of 510 MHz and with fractal configuration, the bandwidth further enhances to 1.12 GHz. The maximum gain measured was found as 11.01 dBi at θ = 10° and ɸ = 360° and 10.45 dBi with fractal configuration. The designed antenna is proposed to be used in RADAR which will be used in the intelligent transportation system for the detection of nearby (short-range) vehicles in the blind zone. This kind of Radar also finds its application in collision avoidance and activating airbags/break boosting and thus helping mankind by saving lives. The article gives an idea of the use of an array antenna in intelligent transportation system for better gain and efficient results.

Research on Task Satellite Selection Method for Space Object Detection LEO Constellation Based on Observation Window Projection Analysis

Aiming at the task planning and scheduling problem of space object detection LEO constellation (SODLC) for detecting space objects in deep space background, a method of SODLC task satellite selection based on observation window projection analysis is proposed. This method projects the spatial relative relationships of the SODLC observation blind zone, observation range, and the initial spatial position of the objects onto the surface of the earth for detectable analysis of satellites and targets and binds the dynamic observation conditions to the satellite trajectory after projection calculation of the visible relationship between target changes. On this basis, combined with the features of SODLC with high orbital symmetry, the task satellite selection is divided into two steps: orbit plane selection and task satellite selection. The orbit planes are selected based on the longitude range of the ascending node with the geographic location of the targets, and the task satellites are selected according to the relative motion relationship between the satellites and the targets together with the constraints of observable conditions. The selection method simplifies the calculation process of scheduling and selecting task satellites. Simulation analysis prove the method has better task satellite selection efficiency. The method has high practical value for task planning and scheduling for event-driven SODLC.

Retrieve and preserve arbitrary polarization states endlessly at uniform high speed

We put forward a novel scheme based on open-loop polarization control (OLPC) to retrieve and preserve arbitrary polarization states endlessly at uniform high speed, with average error of ~0.035 rad and time cost less than 300 μs, which breaks through the limitation of those depend on close-loop polarization control (CLPC). Utilizing perfect modules we build an experimental OLPC system and establish its matrix model with control programme. Results show that the two-unit PC always has blind zone which can not be suppressed to zero, and the blind area centres exactly on the principal state of polarization (PSP) of the second unit. Then we start the third unit to retrieve the SOP from the blind area thus we achieve arbitrary SOPs on the Poincaré sphere endlessly. Subsequently, we demonstrate the great capacity of the OLPC scheme by successfully carrying on retrieving and preserving arbitrary SOPs disturbed by a polarization scrambler, while for sudden and huge disturbance it still shows quite robust and extremely strong. As a result, we fulfill the scheme in practical case of polarization encoded communication system with various environmental disturbance, and further reveal its prominent performance on improvement of signal quality and preservation of reliable communications, which manifests that it is suitable for field applications where exists much disturbance.

Parametric Study of a Blind Spot Zone: Case Studies of Perodua Viva, Perodua Myvi and Proton Suprima


 
 
 The initial works on Blind Spot Zone (BSZ) identification presents the importance of the blind spot towards the everyday drive. The alarming collision rate in the blind spot zone especially when changing lanes has triggered the necessity of BSZ detection and warning system, focusing on a daily-used and affordable car segment. Such technologies are recently available at top variant cars. Therefore, a low cost yet facilitative BSZ detection and warning system is required. This paper presents the continuity experimental result of identification of the BSZ of three different car segments, i.e. Perodua Viva in a compact A-segment car, Perodua Myvi in a compact B-segment and Proton Suprima in a C- segment hatchback. Instead of using volunteered persons, this paper presents a dedicated platform with adjustable heights and camera to replace the human. The results show that the blind spot area and angle is affected by types of car model and driver heights. Also, the relationship between the blind spot area and angle with driver height can be shown in a straight line.
 
 

Identifying Blind Spot Zone for Passenger Cars using Grid-Based Technique


 
 
 A person driving a passenger car depends on the rear view mirror and two side-mounted mirrors to observe the surrounding in order to see vehicles approaching from behind. However, the approaching vehicle may enter a region outside the driver's field of view, making it inconspicuous to the driver. Such a region is known as the blind spot zone (BSZ). Although driving schools emphasize the importance of checking for vehicles in BSZ before attempting to change lane, many fatal collisions have occurred during lane changing. Thus, it is important to understand BSZ particularly its corresponding parameters in order to develop an effective system to detect approaching vehicles and provide warning to the driver. In this paper, a systematic approach using a grid-based technique is proposed to model the BSZ. An experiment was conducted using a commonly used passenger car in Malaysia as a test bed to model the BSZ. Controlled experimental parameters were introduced, and the final results showed that BSZ can be identified using the grid-based technique.
 
 

Surgical Treatment of Iatrogenic Nerve Injury Following Arthroscopic Capsulolabral Repair

Case reports of nerve injuries following arthroscopic capsulolabral repair emphasize the proximity of major nerves to the glenoid. This study describes preoperative localization using nerve-sensitive magnetic resonance imaging in a small cohort of patients with iatrogenic nerve injuries following arthroscopic capsulolabral repair and the outcomes of nerve repair in these patients. Cases of iatrogenic nerve injury following arthroscopic capsulolabral repair referred to 2 surgeons from January 2017 to December 2019 were identified. Clinical charts, electrodiagnostic testing, magnetic resonance imaging studies, and operative reports were reviewed. Four cases of iatrogenic nerve injury were identified. The time to presentation to our institution ranged from 2 weeks to 8 years. The axillary nerves in 3 cases were tethered by a suture at the inferior glenoid, whereas 1 case had a suture tied around the radial and median nerves inferior to the glenohumeral joint capsule. One case underwent excision and nerve transfer, 1 underwent excision and nerve repair, and 2 underwent suture removal and neurolysis. Open and arthroscopic approaches, including a recently described approach to the axillary nerve in the "blind zone," were used. Three cases demonstrated good recovery of all affected motor and sensory functions after surgery. At the 10-month follow-up, 1 case had persistent weakness, but there was evidence of axonal regeneration on electrodiagnostic testing. Arthroscopic capsulolabral repair places regional nerves, particularly the axillary nerve, at risk owing to their proximity to the joint capsule and inferior glenoid. Patients with neuropathic pain in the distribution of affected nerves with corresponding sensorimotor loss following arthroscopic capsulolabral surgery should undergo focused magnetic resonance imaging with nerve-sensitive sequences and electrodiagnostic testing to localize the injury. The use of multiple surgical windows to the axillary nerve in the "blind zone" enables full visualization for neurolysis, suture removal, and nerve repair or transfer. Therapeutic V.

Research progress on intra-articular screw penetration in proximal humeral fracture treated with locking plate

To review the research progress on intra-articular screw penetration in proximal humeral fracture treated with locking plate. The domestic and foreign literature about the proximal humeral fracture treated with locking plate was extensively reviewed. The incidence of screw penetration and risk factors were summarized from both primary and secondary screw penetrations, and the reasons of the intra-articular screw penetration and the technical solutions to avoid the penetration were analyzed. The incidence of intra-articular screw penetration is about 11%-30%, which includes primary and secondary screw penetrations. The primary screw penetration is related to improper operation, inaccurate measurement, and "Steinmetz solid" effect, which results in inadequate fluoroscopy and blind zone. The secondary screw penetration is related to the loss of reduction and varus, collapse, and necrosis of the humeral head. The risk factors for intra-articular screw penetration include the bone mass density, the fracture type, the quality of fracture reduction, the applied location, number, and length of the plate and screws, and whether medial column buttress is restored. Improved fracture reduction, understanding the geometric distribution of screws, good intraoperative fluoroscopy, and reconstruction of medial column buttress stability are the key points for success. The risk of the intra-articular screw penetration in the proximal humeral fractures treated with locking plates is still high. Follow-up studies need to further clarify the cause and mechanism of screw penetration, and the risk factors that lead to screw penetration, in order to effectively prevent the occurrence of this complication.

Design of Polyphase Channelization Algorithm Based on CUDA Stream Architecture

In order to improve the reconfigurability and computing efficiency of the polyphase channelization system, a new algorithm based on CUDA stream architecture was designed and optimized. Firstly, the principle of parallel channelization algorithm without blind zones is introduced. Then, various resource constraints under CUDA architecture and the relationship between the operating efficiency and parameters of the CUDA kernel under these constraints are analysed. The implementation structure of polyphase channelization algorithm is designed. Finally, NVIDIA GPU is used to implement and test the polyphase channelization algorithm based on CUDA stream. The result proves that the computational efficiency of the structure designed in this paper meets the real-time requirements, and can get about 10% efficiency improvement compared with the traditional algorithm.

A Data Fusion Method for Non-Destructive Testing by Means of Artificial Neural Networks.

In the aeronautics sector, aircraft parts are inspected during manufacture, assembly and service, to detect defects eventually present. Defects can be of different types, sizes and orientations, appearing in materials presenting a complex structure. Among the different inspection techniques, Non Destructive Testing (NDT) presents several advantages as they are noninvasive and cost effective. Within the NDT methods, Ultrasonic (US) waves are widely used to detect and characterize defects. However, due the so-called blind zone, they cannot be easily employed for defects close to the surface being inspected. On the other hand, another NDT technique such Eddy Current (EC) can be used only for detecting flaws close to the surface, due to the presence of the EC skin effect. The work presented in this article aims to combine the use of these two NDT methods, exploiting their complementary advantages. To reach this goal, a data fusion method is developed, by using Machine Learning techniques such as Artificial Neural Networks (ANNs). A simulated training database involving simulations of US and EC signals propagating in an Aluminum block in the presence of Side Drill Holes (SDHs) has been implemented, to train the ANNs. Measurements have been then performed on an Aluminum block, presenting tree different SDHs at specific depths. The trained ANNs were used to characterize the different real SDHs, providing an experimental validation. Eventually, particular attention has been addressed to the estimation errors corresponding to each flaw. Experimental results will show that depths and radii estimations error were confined on average within a range of 4%, recording a peak of 11% for the second SDHs.

Research on Penetration Path Planning Method on Near Sea Bottom Based on the Sonar Detection Blind Zone

To improve the survivability and penetration probability of unmanned undersea vehicle(UUV) on near sea bottom combat missions, the factors leading to sonar detection blind zone are analyzed, and the detection blind zone produced by underwater terrain obscuration is mainly studied. A detection range calculation method based on DEM and acoustic ray is proposed, and the simulation study of the near sea bottom penetration path planning is carried out by using terrain blind zone and invasive weed optimization algorithm. Simulation results show the effectiveness of the proposed algorithm. This method can be applied to path planning of the UUV on near sea bottom penetration, which helps to improve Combat effectiveness and Operational effectiveness of UUV.

NOMA-based UAV communications for maritime coverage enhancement

The lack of communication infrastructure in the ocean inevitably leads to coverage blind zones. In addition to high-throughput marine satellites, unmanned aerial vehicles (UAVs) can be used to provide coverage for these blind zones along with onshore base stations. In this paper, we consider the use of UAV for maritime coverage enhancement. Particularly, to serve more ships on the vast oceanic area with limited spectrum resources, we employ non-orthogonal multiple access (NOMA). A joint power and transmission duration allocation problem is formulated to maximize the minimum ship throughput, with the constraints on onboard communication energy. Different from previous works, we only assume the slowly time-varying large-scale channel state information (CSI) to reduce the system cost, as the large-scale CSI is location-dependent and can be obtained according to a priori radio map. To solve the non-convex problem, we decompose it into two subproblems and solve them in an iterative way. Simulation results show the effectiveness of the proposed solution.

Late Pliocene gas detection in-between gas zones using total combinable magnetic resonance (TCMR) in Eastern Mediterranean offshore reservoir

Putting a new concerning to each of the Eastern Mediterranean, offshore plays, gas detection using the most advanced tools, and the zones between gas zones which may not be easily recognized. This was done by adding the total combinable magnetic resonance (TCMR), to density porosity (PHIT-D), and density magnetic resonance porosity (DMRP). X-gas reservoir in the offshore Eastern Mediterranean used as case study. PHIT-D highest result values exist against gas bearing zones with about 29% in X-D5 and lowers at zones not bearing gas with about 6% in X-D3. TCMR highest result values exist against zones not bearing gas with about 49% in X-D5 and lower value zones bearing gas with about 32% in X-1. DMRP in the gas bearing zones does not increase like PHIT-D or decrease like TCMR so it is considered the best gas detector against gas bearing reservoirs and that is very useful. By comparing PHIT-D with DMRP, the gas zones are best detected, but in between zones, some gas zones not detected. By adding TCMR to the comparison, some new gas zones are detected which are lying in-between normal detected gas zones; so, this is a new solution. Interpretation is that PHIT-D is a tool, but DMRP is not a tool and is just integration between two tools: density and NMR. This makes a blind zone between density and DMRP which could be cleared by adding TCMR tools at the same time. The new method will change the producibility from gas reservoirs for the future operations in Eastern Mediterranean plus the previous reservoir production. Also, still applicable to any other gas reservoir.

Multi-aircraft cooperative path planning for maneuvering target detection

<p style='text-indent:20px;'>Multi-aircraft cooperative path planning is a key problem in modern and future air combat scenario. In this paper, this problem is studied in aspect of airborne radar detection to maintain a continuous tracking of a manoeuvring air target. Firstly, the objective function is established in combination with multiple constraints considered, including Doppler blind zone constraint, radar viewing aspect constraint, baseline constraint, and so on. Then, the above optimal control problem is transformed into a nonlinear programming problem with a series of algebraic constraints by hp-adaptive Gauss pseudospectral method (HPAGPM). And it is solved by GPOPS software package based on MATLAB. Simulation results show that the optimized cooperative paths can be got to achieve continuous tracking of maneuvering air target by HPAGPM.</p>

Quantification of soot deposit on a resistive sensor: Proposal of an experimental calibration protocol

During a fire in an industrial facility, the main consequences concerning aerosol are the production of large amount of soot and potential resuspension of hazardous material in particulate form. Soot deposition quantification on walls in a room during a fire is essential for the prediction of aerosol quantities that can be transported in the ventilation ducts and clog high efficiency particulate air filters.For this purpose, accumulative resistive sensors, initially developed for monitoring Diesel Particulate Filters (DPF), have been used to quantify soot particles that are deposited on its sensing side. After validation of the fabrication process via electrical measurements, the sensor response has been studied under different polarization voltages and an experimental protocol for soot quantification has been qualified.Thanks to those protocols, it was first demonstrated that the polarization voltage has no influence on the deposition velocity. Then, the resistive sensor was calibrated at polarization voltages of 10 V and 0.1 V. For 0.1 V, results are less repeatable and do not allow to propose a correlation between conductance and deposited mass. Better repeatability was found for a polarization voltage of 10 V allowing to propose and develop a calibration procedure aiming to correlate sensor conductance and deposited mass of aerosol.Indeed, it was proved that the sensor has a blind zone, in terms of conductance, for mass deposit ranging from 0 to 230 mg/m2. A linear calibration curve with a good sensitivity of 2.49 μS mg-1.m2 was obtained for deposited mass between 230 and 1630 mg/m2.

The trajectories of extracurricular learning of children in Muslim families of the Republic of Bashkortostan

The subject of this research is the trajectories of extracurricular learning in Muslim families of the Republic of Bashkortostan. The educational trajectories of various ethno-confessional groups have certain focus areas or “blind zones” substantiated by the religious worldview, ethnic specificity, and other sociocultural factors. Muslim community of the Republic of Bashkortostan is also concerned with the problem of conveying cultural values to the next generation. The trajectories of extracurricular leaning of the children from religious families are reflected in a number of patterns that differ from the educational path of their agemates. The author determines the focus areas in upbringing and educational tasks of the Muslim families, the range of pedagogical literature of Muslim parents, as well as the main forms of extracurricular learning of children in Muslim families and the role of religious education therein. The article provides the results of sociological survey, which demonstrates that the physical and intellectual development of children is the priority vectors for the Muslim parents; while, for example, aesthetic development is not as important. It is also underlined that Muslim families not always can afford the desirable amount of activities for their children.

High-efficiency, flexibility and lead-free X-ray shielding multilayered polymer composites: layered structure design and shielding mechanism

To overcome the severe toxicity and blind absorption zone of conventional lead-based shielding materials for X-rays in the 70–90 keV range, the lead-free multilayered polymer composites were designed and fabricated. The effects of the direction of incidence of the X-rays and number of layers as well as layer thickness ratio of the (tungsten/ethylene-octene copolymer)/(bismuth/ethylene-octene copolymer) layered composites on their shielding efficiency were studied systematically. Compared to the traditional polymer blending, the multilayered polymer composites exhibited the improved photon attenuation. The multilayered polymer composites (layer thickness ratio was 3:7) with 6 layers had the best X-ray shielding ability. Moreover, the X-ray shielding provided by the multi-layered interfaces and the multiple complementary effect of the absorption within the multilayered structure were firstly proposed based on computer simulations. The multilayered structural design effectively weakened the probability of the X-ray penetration. Therefore, the X-ray shielding capability can be effectively enhanced through increasing number of layers and the synergistic effect of multi-layered interfaces. The experimental results of this study can serve as guidelines for the fabrication of flexibility, lead-free, lightweight and high-efficiency X-ray shielding materials.

Multi-GMTI fusion for Doppler blind zone suppression using PHD fusion

For ground moving target indication (GMTI) sensor tracking, the existence of the Doppler blind zone (DBZ) seriously deteriorates tracking performance. In order to minimize the adverse effects of the DBZ factor, this paper puts forward the idea of using sensor fusion technique to suppress the DBZ masking problem. First, we derive the probability hypothesis density (PHD) fusion under the generalized covariance intersection (GCI) framework and its Gaussian mixture (GM) implementation for fusing local PHDs from the local trackers. However, we find that there is the problem of cardinality underestimation (CUE) in the original PHD fusion, which is exacerbated when targets are masked by the DBZ. After analyzing this problem in detail, we propose an improved PHD fusion algorithm through operations such as scale coefficient correction, GM component partition, and fused label correction. Finally, the feasibility and effectiveness of the proposed fusion are verified through numerical examples, and it is proved that it alleviates the CUE problem and is significantly better than local trackers.

Study on project trajectory of air-to-ground missile with strapdown seeker under multi constraints

The air-to-ground missile with strapdown seeker may have the problems, including small field of view(FOV), limited overload, and fall angle constraint. To solve the above mentioned problem, a phased guidance scheme is proposed. In this scheme, the attack trajectory is divided into the following six stages, including glided stage, fall angle constraint stage, target acquisition and adjustment stage, terminal guidance stage and blind zone stage. The glided stage is designed to increase range, the terminal fall angle is attained ahead of time at fall angle constraint stage. The aim of target acquisition and adjustment stage is to adjust the missile attitude, so that the target will fall within the FOV of the seeker. It creates good condition to capture the target for strapdown seeker. In the terminal stage, the guidance law of proportional navigation and attitude track are used to fit the needs of FOV constraint and attack accuracy. The simulation result shows that the project trajectory can solve the application of attacking moving targets for air-to-ground missile with strapdown seeker under multi constraints.