Mechanism of Defects and Electrode Structure on the Performance of AlN-based Metal Semiconductor Metal Detectors

We used the metal-organic chemical vapor deposition(MOCVD) method to grow AlN material on a c-plane sapphire substrate and fabricate an AlN-based metal-semiconductor-metal (MSM) detector. Analyzing the influence mechanism of different dislocation densities in AlN materials and detector electrode structure on the detector performance, it was found that the lower the dislocations can effectively reduce the dark current of the detector under zero bias voltage, and help improve the performance of the detector. The study also found that when the finger spacing of the detector remained the same and the finger width increased, the efficiency of the detector decreased, while the response time of the detector increased, when the finger width of the detector electrodes remained unchanged and the finger spacing increased, the response time of the detector increased. Therefore, the electrode finger width and finger spacing must be compromised in the design of the electrode structure to improve the performance of the AlN-based MSM detector.

Experimental Stand for Sorting Components Dismantled from Printed Circuit Boards

There is nothing new about the fact that higher concentrations (up to 50 times) of valuable materials can be found in e-waste, compared to mined ores. Moreover, the constant accumulation of excessive amounts of waste equipment has a negative impact on the environment. The components found in electronic equipment may contain hazardous materials or materials that could be recycled and reintroduced into production processes, thus reducing the carbon footprint created by waste electrical and electronics equipment (WEEE). Sustainable e-waste recycling requires high-value, integrated recovery systems. By implementing a two-stage experimental sorting stand, this paper proposes an efficient and fast sorting method that can be industrially scaled up to reduce the time, energy and costs needed to sort electronic waste (e-waste). The sorting equipment is in fact an ensemble of sensors consisting of cameras, color sensors, proximity sensors, metal detectors and a hyperspectral camera. The first stage of the system sorts the components based on the materials’ spectral signature by using hyperspectral image (HSI) processing and, with the help of a robotic arm, removes the marked components from the conveyor belt. The second stage of the sorting stand uses a contour vision camera to detect specific shapes of the components to be sorted with the help of pneumatic actuators. The experimental sorting stand is able to distinguish up to five types of components with an efficiency of 89%.

An Improved Chaotic Detection System for Metal Detectors

This paper first applies a chaotic system-Duffing oscillator to a metal detector, and uses RHR algorithm to compute two Lyapunov characteristics exponents of the Duffing system. In this way, the two Lyapunov characteristic exponents can help to judge the Duffing system being chaotic or not quantitatively. And also help to get the threshold value more accurately. Then a simulation model of Duffing system fit for detectors is established by Matlab. Simulation results indicate that an suitable Duffing system can improve the sensitivity of a detector effectively.

SPATIAL 3D DOCUMENTATION OF HISTORICAL MINING REMNANTS IN FORESTED AREA IN THE ERZGEBIRGE/KRUŠNOHOŘÍ MINING REGION UNESCO SITE

This contribution deals in the possibilities of 3D documentation of historical mining relicts hidden in the forest. On the Czech – German border, in the Ore Mountains, several historical mining relicts are located there. There are interesting underground spaces (historical mines), some of which have recently been made available for visits by tourists. But there are many relicts on the surface that are linked to mining and are not known or on the fringes of interest. These are mining pits, dumps, water works, remains of buildings and historic entrance roads. Many of them are in forest areas, were not documented or archaeologically explored, and have recently been devastated by amateur collectors equipped with metal detectors who unfortunately destroy unexplored localities to find interesting relicts. For the basic documentation and delimitation of these objects, aerial laser scanning (ALS) and personal laser mobile scanning (PLS) were used; some finds were documented by close-range photogrammetry.

IOT based Land Mine Detection Robot

Such equipment is usually automatically blasted through pressure when a target steps on it or drives on it. Demining or mine clearance is the process of removing land mines from an area, while minesweeping describes the task of locating mines. Landmines are generally easy to lay and difficult and dangerous. They are harmful due to their unknown positions and are often difficult to detect. Although dimming has been given the highest priority, currently my clearing operation is a labor-intensive, slow, very dangerous, expensive and low technology operation. The current rate of human quarry is about 100 thousand per year. The idea is to build and develop an automated robot capable of detecting buried landmines and taking them from their locations, enabling the operator to control the robot from afar. The buried quarry is detected using metal detectors as most land mines have metal components. The robot will travel in a straight line route. The system allows the operator to stay at a safe distance by enabling the robot to safely control. Wireless control is for the safety of the operator, designed robots must be able to operate remotely, and is equipped with wireless data transmission capabilities.

A Detection System with Spider Web Coil-Based Wireless Charging and an Active Battery Management System

The article presents a detection system with spider web coil-based wireless charging. Commonly available metal detectors are sold as handheld systems, which enable only progressive, lengthy, time-consuming search. Importantly, a part of the investigated area can thus be easily missed, and the probability that a metal object will not be found increases substantially. This problem, however, is eliminable via the automatic position tracking mode embedded in the solution obtained through our research. The proposed system facilitates using the spider web coil simultaneously for wireless charging and metal detection by pulse induction. The topology of the detector can emit variable pulse lengths, thus allowing the device to detect more types of metal and to adapt itself to the permeability of the soil. The coil has a branch in a relevant part of the winding to reduce undesirable electromagnetic interference during the charging. On the transmitting side of the topology, impedance matching is included to maintain the maximum spatial gap variability. By changing the position of the receiving side, the output voltage changes; therefore, a high efficiency DC/DC converter is employed. The individual battery cells demonstrate different internal resistances, requiring us to apply a new method to balance the cells voltage. The system can be utilized on self-guided vehicles or drones; advantageously, a GPS resending the coordinates to a mesh radio allows for accurate positioning. With the mesh topology, potential cooperation between the multiple systems is possible. The setup utilizes the same coil for wireless power transfer and detection.

ASSESSING CONGREGANTS PERCEPTION OF VULNERABILITY OF CHURCH BUILDINGS TO SECURITY THREATS IN NAIROBI COUNTY, KENYA

This paper uses data collected for an MA Thesis on Assessing Congregants’ perception of Vulnerability of Church Buildings to security threats in Nairobi County, Kenya. The study has been necessitated by increased cases of targeted criminal attacks on congregants and church buildings in addition to increased perceptions of congregants as soft targets of insecurity, more pertinently in Nairobi County. The study will be guided by the following objectives; to investigate the nature of perceived vulnerability against church buildings; to explore congregant’s perceptions of what constitutes church buildings security and safety; to establish congregant’s perceptions of their level of preparedness in case of a criminal attack while in church buildings service; and to determine the congregant’s perceptions of what they think should be done to secure church buildings in Nairobi County Kenya. This study was grounded by two theories; Defensive Space Concept and Crime Prevention through Environmental Design (CPTED). This study adopted a cross-sectional survey design while Stratified random sampling technique was used to pick all the main respondents. Questionnaires were used to collect data from 182 members of each church (main respondents). In addition, Key Informants (K.I) guide was used to collect qualitative data from 8 K.I who include 4 Priests (1 from each church), and 4 security guards (one from each church). Data was analyzed with the aid of Statistical Package for Social Sciences (SPSS) and results presented using tables, bar and pie charts. The study results revealed that violent attacks against the churches in Nairobi county are on the increase (72%) and that the violent attacks against the churches in Nairobi county have inspired fear among church attendants (68.1%). Further, results showed the gun attacks were the most prevalent in church buildings (29.7%) closely followed by knife attacks (29.1%), explosive attacks (20.3%), suicide bombs (13.2%). Further, the results have revealed that some churches had employed various measures to counter violent attacks that included amongst other measures employed full time trained security staff to manage such incidents. Congregant’s perceptions on violent attacks against churches include; Knife and explosive attacks during services, but which have prompted fears of future gun or other terror attacks as is the case in other countries. According to the study; main measure of church security and safety included the Perimeter Walls, use of Surveillance cameras, use of Metal Detectors in church entrances, and heavy barriers in church entrance amongst other measures. As a policy measure, the study recommended formulation of standard security and safety measures applicable to all places of worship in Kenya that include; permanent security staff and armed security in all places of worship.