International Science Index

International Journal of Electronics and Communication Engineering

Simulation and Experimentation Investigation of Infrared Non-Destructive Testing on Thermal Insulation Material
The heat-resistant material has important application in the aerospace field. The reliability of the connection between the heat-resisting material and the body determines the success or failure of the project. In this paper, lock-in infrared thermography non-destructive testing technology is used to detect the stability of the thermal-resistant structure. The phase relationship between the temperature and the heat flow is calculated by the numerical method, and the influence of the heating frequency and power is obtained. The correctness of the analysis is verified by the experimental method. Through the research, it can provide the basis for the parameter setting of heat flux including frequency and power, improve the efficiency of detection and the reliability of connection between the heat-resisting material and the body.
An Integrated Tailoring Method for Thermal Cycling Tests of Spacecraft Electronics
Thermal tests of electronic units are critically important for the reliability validation and performance demonstration of the spacecraft hard-wares. The tailoring equation in MIL-STD-1540 is based on fatigue of solder date. In the present paper, a new test condition tailoring expression is proposed to fit different thermo-mechanical fatigue and different subsystems, by introducing an integrated evaluating method for the fatigue acceleration exponent. The validate test has been accomplished and the data has been analyzed and compared with that from the MIL-STD-1540 tailoring equations. The results are encouraging and reasonable.
Stability of Porous SiC Based Materials under Relevant Conditions of Radiation and Temperature
SiC based composites are candidates for possible use as structural and functional materials in the future fusion reactors, the main role is intended for the blanket modules. In the blanket, the neutrons produced in the fusion reaction slow down and their energy is transformed into heat in order to finally generate electrical power. In the blanket design named Dual Coolant Lead Lithium (DCLL), a PbLi alloy for power conversion and tritium breeding circulates inside hollow channels called Flow Channel Inserts (FCIs). These FCI must protect the steel structures against the highly corrosive PbLi liquid and the high temperatures, but also provide electrical insulation in order to minimize magnetohydrodynamic interactions of the flowing liquid metal with the high magnetic field present in a magnetically confined fusion environment. Due to their nominally high temperature and radiation stability as well as corrosion resistance, SiC is the main choice for the flow channel inserts. The significantly lower manufacturing cost presents porous SiC (dense coating is required in order to assure protection against corrosion and as a tritium barrier) as a firm alternative to SiC/SiC composites for this purpose. This application requires the materials to be exposed to high radiation levels and extreme temperatures, conditions for which previous studies have shown noticeable changes in both the microstructure and the electrical properties of different types of silicon carbide. Both initial properties and radiation/temperature induced damage strongly depend on the crystal structure, polytype, impurities/additives that are determined by the fabrication process, so the development of a suitable material requires full control of these variables. For this work, several SiC samples with different percentage of porosity and sintering additives have been manufactured by the so-called sacrificial template method at the Ceit-IK4 Technology Center (San Sebastián, Spain), and characterized at Ciemat (Madrid, Spain). Electrical conductivity was measured as a function of temperature before and after irradiation with 1.8 MeV electrons in the Ciemat HVEC Van de Graaff accelerator up to 140 MGy (~ 2·10 -5 dpa). Radiation-induced conductivity (RIC) was also examined during irradiation at 550 ºC for different dose rates (from 0.5 to 5 kGy/s). Although no significant RIC was found in general for any of the samples, electrical conductivity increase with irradiation dose was observed to occur for some compositions with a linear tendency. However, first results indicate enhanced radiation resistance for coated samples. Preliminary thermogravimetric tests of selected samples, together with posterior XRD analysis allowed interpret radiation-induced modification of the electrical conductivity in terms of changes in the SiC crystalline structure. Further analysis is needed in order to confirm this.
Economics of Open and Distance Education in the University of Ibadan, Nigeria
One of the major objectives of the Nigeria national policy on education is the provision of equal educational opportunities to all citizens at different levels of education. With regards to higher education, an aspect of the policy encourages distance learning to be organized and delivered by tertiary institutions in Nigeria. This study, therefore, determines how much of the Government resources are committed, how the resources are utilized and what alternative sources of funding are available for this system of education. This study investigated the trends in recurrent costs between 2004/2005 and 2013/2014 at University of Ibadan Distance learning Centre. A descriptive survey research design was employed for the study. Questionnaire was the research instrument used for the collection of data. The population of the study was two hundred and eighty (280) current distance learning education students, seventy (70) academic staff and fifty (50) administrative staff. Only three hundred and fifty four (354) questionnaires were correctly filled and returned. Data collected were analyzed and coded using the frequencies, ratio, average and percentages were used to answer all the research questions. The study revealed that staff salaries and allowances of academic and non-academic staff represent the most important variable that influences the cost of education. About 55% of resources were allocated to this sector alone. The study also indicates that costs rise every year with increase in enrolment representing a situation of diseconomies of scale. This study recommends that universities who operates distance learning programme should strive to explore other internally generated revenue option to boost their revenue. University of Ibadan being the premier university in Nigeria should be given foreign aids, and home supports both financially and materially to enable her run a formidable distance education that would measure up in planning and implementation with those of developed nation.
Cavity-Type Periodically-Poled LiNbO₃ Device for Highly-Efficient Third-Harmonic Generation
We develop a periodically-poled LiNbO₃ (PPLN) device for highly-efficient third-harmonic generation (THG), where the THG efficiency is enhanced with a cavity. THG can usually be produced via χ⁽³⁾-nonlinear materials by optical pumping with very high pump-power. Instead, we here propose THG by moderate-power pumping through a specially-designed PPLN device containing only χ⁽²⁾-nonlinearity, where sum-frequency generation in the χ⁽²⁾ process is employed for the mixing of a pump beam and a second-harmonic-generation (SHG) beam produced from the pump beam. The cavity is designed to increase the SHG power with dichroic mirrors attached to both ends of the device that perfectly reflect the SHG beam back to the device and yet let the pump and THG beams pass through the mirrors. This brings about a THG-power enhancement because of THG power proportional to the enhanced SHG power. We examine the THG-efficiency dependence on the pump power and show that very high THG-efficiency is obtained at moderate pump-power when compared with that of a cavity-free PPLN device.
Bluetooth Piconet System for Children Care Applications
This study mainly concerns a safety device designed for child care. When children are out of sight or the caregivers cannot always pay attention to the situation, through the functions of this device, caregivers can immediately be informed to make sure that the children do not get lost or hurt, and thus, ensure their safety. Starting from the concept, the device is produced based on the relatively low-cost Bluetooth piconet system and a three-axis gyroscope sensor. This device can transmit data to a mobile phone APP through Bluetooth, in order that the user can learn the situation at any time. By simply clipping the device in a pocket or on the waist, after switching on/starting the device, it will send data to the phone to detect the child’s fall and distance. Once the child is beyond the angle or distance set by the APP, it will issue a warning to inform the phone owner.
An Intelligent Baby Care System Based on IoT and Deep Learning Techniques
Due to the heavy burden and pressure on caring the infants, an integrated automatic baby watching system based on IoT smart sensing and deep learning machine vision techniques is proposed in this paper. By monitoring the infant body conditions such as heartbeat, breathe, body temperature, sleeping posture, as well as the surrounding conditions such as stab objects, light, noise, humidity and temperature, the proposed system can analyze and predict the obvious/potential dangerous conditions according to the observing data and then adopt suitable actions in real time to prevent the infant from hurt. Thus reduce the burden of the caregiver and improve safety efficiency of the caring work. The experimental results show that the proposed system works successfully for the infant caring work thus can be implemented in various life fields practically.
Minimum Half Power Beamwidth and Side Lobe Level Reduction of Linear Antenna Array Using Particle Swarm Optimization
In this paper the optimization performance of non-uniform linear antenna array is presented. The Particle Swarm Optimization (PSO) algorithm is presented to minimize Side Lobe Level (SLL) and Half Power Beamwidth (HPBW). The purpose of using the PSO algorithm is to get the optimum values for inter-element spacing and excitation amplitude of linear antenna array that provides a radiation pattern with minimum SLL and HPBW. Various design examples are considered and the obtain results using PSO are confirmed by comparing with results achieved using other nature inspired metaheuristic algorithms such as real coded genetic algorithm (RGA) and biogeography (BBO) algorithm. The comparative results show that optimization of linear antenna array using the PSO provides considerable enhancement in the SLL and HPBW.
Interactive Winding Geometry Design of Power Transformers
Winding geometry design is an important part of power transformer electrical design. Conventionally, the winding geometry is designed manually, which is a time-consuming job because it involves many iteration steps in order to meet all cost, manufacturing and electrical requirements. Here a method is presented which automatically generates the winding geometry for given user parameters and allows the user to interactively set and change parameters. To achieve this goal, the winding problem is transferred to a mixed integer nonlinear optimization problem. The relevant geometrical design parameters are defined as optimization variables. The cost and other requirements are modeled as constraints. For the solution, a stochastic ant colony optimization algorithm is applied. It is well-known, that an optimizer can get stuck in a local minimum. For the winding problem, we present efficient strategies to come out of local minima, furthermore a reduced variable search range helps to accelerate the solution process. Numerical examples show that the optimization result is delivered within seconds such that the user can interactively change the variable search area and constraints to improve the design.
Happiness, Media and Sustainability of Communities in Donkeaw, Mearim District, Chiang Mai
This study of the ‘happiness’ and ‘sustainability’ in the community of Donkeaw, Amphoe Mae Rim, Chiang Mai Province during the non-election period in Thailand, noted that their happiness levels are in the middle-average range. This was found using a mixed approach of qualitative and quantitative methods (N=386, α=0.05). The study explores indicators for six aspects of well-being and happiness, including, good local governance, administrative support for the health system that maintains people’s mental and physical health, environment and weather, job security and a regular income aids them in managing a sustainable lifestyle. The impact of economic security and community relationships on social and cultural capital, and the way these aspects impact on the life style of the community, affects the sustainable well-being of people. Moreover, living with transparency and participatory communication led to diverse rewards in many areas.
Design of an Automatic Windshield-Breaking Device for Abnormal Situation in Moving Vehicles
This research is to design a device to deal with an emergency situation in which abnormal gas produced or vehicle is accidentally drawn into water or driven into a sewer. The device is put at the corner of front windshield and connected to mobile phone through Bluetooth interface. Once the situation is happened, it would break the windshield and, at the same time, make an emergency call to call on the following rescuing action. The device operated are divided into two steps to prevent making mistakes on detecting water level or abnormal gas concentration. The first alarm is the primitive judgment condition, which enables the driver to react the situation. Once the second alarm is happened, the system would recognize the primitive reaction is invalid or inefficient, the driver is in danger and the windshield should be break immediately. This design is to the greatest extent prevent unnecessarily damaging the car and to ensure the safety of the driver and passengers.
E-Learning System for Automatic Generation and Evaluation of Per-Student Customized Tasks for Hardware Modeling Courses
VHDL is a powerful hardware description language to describe algorithms and functionalities to be automatically converted to digital circuits. Therefore it is an important instrument which students should learn. Unfortunately, decreasing teacher-to-student ratios limit the possibilities to offer a personalized guidance based on the students’ needs. The declared goal of the VHDL E-Learning System (VELS) is to give students the possibilities to learn at their own pace and learn from their own mistakes while considering their previous knowledge. VELS is a flexible tool that, once configured, fully automatically generates individual VHDL assignments for students and receives VHDL models submitted by students. It simulates and checks these models, approves or gives feedback on these models, and allows multiple submissions such that students can improve their models iteratively. The VHDL E-Learning System is a Python based daemon on a remote server, and the interaction with students is performed via email. The assignments are parameterized such that every student gets a different variant of the problem. After configuration VELS interacts fully automatically with the students and no tutor intervention is required. This facilitates large classes while each student can still get many assignments, try various solutions and get them checked. Thus, students can work at any place and time of their own choice. Various features provide flexibility for teachers: 1) A tool that intuitively assists in defining new tasks, 2) An interface to add support for different simulation backends, 3) A web interface to configure tutored and untutored courses, 4) An exam mode for university labs with no internet access, 5) Different scheduling modes: free task selection or strict sequence of assignments. 15 different task families have been implemented, from basic boolean functions up to modeling a simple but complete microcomputer. The main work to generate a new task is to formulate the assignment precisely, unambiguously, and to design the testbench that is deployed by VELS to check submitted solutions. VELS has been used for two years in four courses, two at the undergraduate and two at the graduate level. In total over 700 students have used the system. The tool is published under the open-source license GPLv2, making it freely accessible to teachers at schools and universities around the globe. This paper describes the goals and intention of the system, its design and implementation, and the experience of running and using it.
Design of Ink-Printed Radio Frequency Identification Tags for Electronic Article Surveillance Systems
Electronic Article Surveillance (EAS) tag plays an important role in securing products and managing inventory in the new era of global trade. The current cost of the conventional fabrication method of EAS tags forms the bottleneck that prevents pervasive item-level security. However, emerging ink-printed electronics suggests a promising technology to reduce the cost of an EAS tag. This paper aims to determine the dominant factors that affect the performance of conductive ink printed EAS tags operating at 8.2 MHz. First, an EAS tag is designed using High Frequency Structural Simulator (HFSS), which includes a square spiral inductor and a capacitor. We evaluate the performance of the tag in terms of resonant frequency and the quality factor (Q), while considering different values for the length of spiral inductor coil and ink thickness. In addition, a printed vertical interconnect access (VIA) is also proposed for fabricating multilayer printed electronics. Simulation results reveal that the tag with λ/50 as the length of spiral inductor coil offers the highest Q factor.
Improved Small-Signal Characteristics of Infrared 850nm Top-Emitting Vertical-Cavity Lasers
High-speed infrared vertical-cavity surface-emitting laser diodes (VCSELs) with Cu-plated heat sinks were fabricated and tested. VCSELs with 10um aperture diameter and 4um of electroplated copper demonstrated a -3dB modulation bandwidth (f-3dB) of 14GHz and a resonance frequency (fR) of 9.5GHz at a bias current density (Jbias) of only 4.3 kA/cm², which corresponds to an improved f-3dB²/Jbias ratio of 44GHz²/kA/cm². At higher and lower bias current densities the f-3dB²/ Jbias ratio decreased to about 18 GHz²/kA/cm² and 30 GHz²/kA/cm², respectively. Examination of the analogue modulation response demonstrated that the presented VCSELs displayed a steady f-3dB/ fR ratio of 1.41 ± 10% over the whole range of the bias current (1.3Ith to 6.2Ith). The devices also demonstrated a maximum modulation bandwidth (f-3dB max) of more than 16GHz at a bias current less than the industrial bias current standard for reliability by 25%.
Encapsulation of Flexible OLED with an Auxiliary Sealing Line
Flexible OLED is an important technology for the next generation display over various kinds of applications. However, the organic materials of OLEDs degrade rapidly under the invasion of oxygen and water moisture. The degradation causes the formation of non-emitting areas which gradually suppress the device brightness, ultimately the lifetime of the device decreasing rapidly. Until now, the most suitable sealing process of the flexible OLED devices is a thin film encapsulation (TFE). However, TFE consists of a multilayer thin-film structure with organic-inorganic materials, so the cost is expensive and the process time is long. Another problem is that the blocking characteristics from the moisture and oxygen are not perfect. Therefore, the encapsulation of the flexible OLED device is a still key technical issue for the successful market entry. In this study, we are to introduce an auxiliary sealing line between the two flexible substrates. The electrode lines were formed on the substrates which have a SiNx barrier coating layer. To induce the solid phase diffusion process between the SiNx layer and the electrode lines, the electrode materials were determined as Al-Si composition. Thermal energy was supplied for both the SiNx layer and Al-Si electrode lines within the furnace to induce the interfacial bonding through the solid phase diffusion of Si. We printed a test pattern for the edge of the flexible PET substrate of 3cm*3cm size. Experimental conditions such as heating temperature, heating time were optimized to get enough adhesion strength which was estimated through the competitive bending test. Finally, OLED devices with flexible PET substrate of 3cm*3cm size were manufactured to investigate the blocking characteristics as an encapsulation layer.
A Hop-By-Hop Transport Control Protocol for Navigation Satellite Network
Due to the constraints of navigation satellite and directional inter-satellite-link (ISL) antenna, the number of antennas that can be equipped on one navigation satellite is limited (e.g. only one ISL can be equipped). The ISLs of navigation satellite will be half-duplex and intermittent available, thus forming a time division multiplexing navigation satellite network. For network like this, the design of network protocol, especially the transport control protocol, is the key issue to provide efficient data transport service. This paper focuses on transport control protocol for time division multiplexing navigation satellite network. Since traditional end-to-end transport control protocol doesn’t perform well in such network, this paper proposes a hop-by-hop transport control protocol which has the following features: firstly, as the path is not available at all time, message will be stored in persistent storage of network nodes to wait for communication opportunity; secondly, the proposed hop-by-hop transport control protocol utilize automatic repeat request to achieve reliable transport and the acknowledgment and re-transmission will be performed between adjacent nodes rather than between source and destination nodes. Simulation results show that the data throughput of the proposed hop-by-hop transport control protocol is higher than traditional end-to-end transport control protocol. The traffic can also move more quickly and distribute more uniform.
The On-Board Critical Message Transmission Design for Navigation Satellite Delay/Disruption Tolerant Network
The navigation satellite network, especially the Beidou MEO Constellation, can relay data effectively with wide coverage and is applied in navigation, detection, and position widely. But the constellation has not been completed, and the amount of satellites on-board is not enough to cover the earth, which makes the data-relay disrupted or delayed in the transition process. The data-relay function needs to tolerant the delay or disruption in some extension, which make the Beidou MEO Constellation a delay/disruption-tolerant network (DTN). The traditional DTN designs mainly employ the relay table as the basic of data path schedule computing. But in practical application, especially in critical condition, such as the war-time or the infliction heavy losses on the constellation, parts of the nodes may become invalid, then the traditional DTN design could be useless. Furthermore, when transmitting the critical message in the navigation system, the maximum priority strategy is used, but the nodes still inquiry the relay table to design the path, which makes the delay more than minutes. Under this circumstances, it needs a function which could compute the optimum data path on-board in real-time according to the constellation states. The on-board critical message transmission design for navigation satellite delay/disruption-tolerant network (DTN) is proposed, according to the characteristics of navigation satellite network. With the real-time computation of parameters in the network link, the least-delay transition path is deduced to retransmit the critical message in urgent conditions. First, the DTN model for constellation is established based on the time-varying matrix (TVM) instead of the time-varying graph (TVG); then, the least transition delay data path is deduced with the parameters of the current node; at last, the critical message transits to the next best node. For the on-board real-time computing, the time delay and misjudges of constellation states in ground stations are eliminated, and the residual information channel for each node can be used flexibly. Compare with the minute’s delay of traditional DTN; the proposed transmits the critical message in seconds, which improves the re-transition efficiency. The hardware is implemented in FPGA based on the proposed model, and the tests prove the validity.
Design of Data Management Software System Supporting Rendezvous and Docking with Various Spaceships
The function of the two spacecraft docking network, the communication and control of a docking target with various spacecrafts is realized in the space lab data management system. In order to solve the problem of the complex data communication mode between the space lab and various spaceships, and the problem of software reuse caused by non-standard protocol, a data management software system supporting rendezvous and docking with various spaceships has been designed. The software system is based on CCSDS Spcecraft Onboard Interface Service(SOIS). It consists of Software Driver Layer, Middleware Layer and Appliaction Layer. The Software Driver Layer hides the various device interfaces using the uniform device driver framework. The Middleware Layer is divided into three lays, including transfer layer, application support layer and system business layer. The communication of space lab plaform bus and the docking bus is realized in transfer layer. Application support layer provides the inter tasks communitaion and the function of unified time management for the software system. The data management software functions are realized in system business layer, which contains telemetry management service, telecontrol management service, flight status management service, rendezvous and docking management service and so on. The Appliaction Layer accomplishes the space lab data management system defined tasks using the standard interface supplied by the Middleware Layer. On the basis of layered architecture, rendezvous and docking tasks and the rendezvous and docking management service are independent in the software system. The rendezvous and docking tasks will be activated and executed according to the different spaceships. In this way, the communication management functions in the independent flight mode, the combination mode of the manned spaceship and the combination mode of the cargo spaceship are achieved separately. The software architecture designed standard appliction interface for the services in each layer. Different requirements of the space lab can be supported by the use of standard services per layer, and the scalability and flexibility of the data management software can be effectively improved. It can also dynamically expand the number and adapt to the protocol of visiting spaceships. The software system has been applied in the data management subsystem of the space lab, and has been verified in the flight of the space lab. The research results of this paper can provide the basis for the design of the data manage system in the future space station.
Research and Application of Consultative Committee for Space Data Systems Wireless Communications Standards for Spacecraft
According to the new requirements of the future spacecraft, such as networking, modularization and non-cable, this paper studies the CCSDS wireless communications standards, and focuses on the low data-rate wireless communications for spacecraft monitoring and control. The application fields and advantages of wireless communications are analyzed. Wireless communications technology has significant advantages in reducing the weight of the spacecraft, saving time in spacecraft integration, etc. Based on this technology, a scheme for spacecraft data system is put forward. The corresponding block diagram and key wireless interface design of the spacecraft data system are given. The design proposal of the wireless node and information flow of the spacecraft are also analyzed. The results show that the wireless communications scheme is reasonable and feasible. The wireless communications technology can meet the new demands of the future spacecraft in networking, modularization and non-cable.
A High Reliable Space-Borne File System with Applications of Device Partition and Intra-Channel Pipeline in Nand Flash
As an inevitable chain of the space data acquirement system, space-borne storage system based on Nand Flash has gradually been implemented in spacecraft. In face of massive, parallel and varied data on board, efficient data management become an important issue of storage research. Face to the requirements of high-performance and reliability in Nand Flash storage system, a combination of hardware and file system design can drastically increase system dependability, even for missions with a very long duration. More sophisticated flash storage concepts with advanced operating systems have been researched to improve the reliability of Nand Flash storage system on satellites. In this paper, architecture of file system with multi-channel data acquisition and storage on board is proposed, which obtains large-capacity and high-performance with the combine of intra-channel pipeline and device partition in Nand Flash. Multi-channel data in different rate are stored as independent files with parallel-storage system in device partition, which assures the high-effective and reliable throughput of file treatments. For massive and high-speed data storage, an efficiency assessment model is established to calculate the bandwidth formula of intra-channel pipeline. Information tables designed in Magnetoresistive RAM (MRAM) hold the management of bad block in Nand Flash and the arrangement of file system address for the high-reliability of data storage. During the full-load test, the throughput of 3D PLUS Module 160Gb Nand Flash can reach 120Mbps for store and reach 120Mbps for playback, which efficiently satisfies the requirement of multi-channel data acquisition in Satellite. Compared with previous literature, the results of experiments verify the advantages of the proposed system.
Automatic Post Stroke Detection from Computed Tomography Images
For detecting strokes, Computed Tomography (CT) scan is preferred for imaging the abnormalities or infarction in the brain. Because of the problems in the window settings used to evaluate brain CT images, they are very poor in the infarction detection. A default window setting is used for evaluating the CT images, but it is unable to properly enhance the contrast of the hyper infarction or post-stroke regions in the brain. In the default window setting, the window centre (WC) is fixed to 40HU, which corresponds to the Hounsfield value (HU) of the central brain soft tissue and the window width (WW) is varied manually each time according to the application. But the post-stroke regions are not observable with these default window settings, which leads to misinterpretation by the radiologists. This paper presents a novel automatic estimation method for the window settings of the CT images for the proper contrast of the hyper infarction present in the brain. In the proposed work the window width is estimated automatically for each slice, and the window centre is changed to a new value of 31HU, which is the average of the HU values of the gray matter and white matter in the brain. The automatic window width estimation is based on the average of median of statistical central moments. The estimated window width is different for each CT slice, depending upon the statistical properties of the slice. Thus with the new suggested window centre and estimated window width, the hyper infarction or post-stroke regions in CT brain images are properly detected. The automatic window width estimation technique with the window centre 31HU improved the contrast of the post-stroke region and also avoids the manual window width tuning. The proposed approach assists the radiologists in CT evaluation and improves the efficiency of the post-stroke region diagnosis. Hence early quantitative signs of delayed stroke, which leads to severe hemorrhage in the future can be prevented by providing timely medication to the patients.
A Sparse Representation Speech Denoising Method Based on Adapted Stopping Residue Error
A sparse representation speech denoising method based on adapted stopping residue error was proposed in this paper. Firstly, the cross-correlation between the clean speech spectrum and the noise spectrum was analyzed, and an estimation method was proposed. In the denoising method, an overcomplete dictionary of the clean speech power spectrum was learned with the K-Singular Value Decomposition (K-SVD) algorithm. In the sparse representation stage, the stopping residue error was adaptively achieved according to the estimated cross-correlation and the adjusted noise spectrum, and the orthogonal matching pursuit (OMP) approach was applied to reconstruct the clean speech spectrum from the noisy speech. Finally, the clean speech was re-synthesis via the inverse Fourier transform with the reconstructed speech spectrum and the noisy speech phase. The experiment results show that the proposed method outperforms the conventional methods in terms of subjective and objective measure.
Change Detection Method Based on Scale-Invariant Feature Transformation Keypoints and Segmentation for Synthetic Aperture Radar Image
Synthetic aperture radar (SAR) image change detection has recently become a challenging problem owing to the existence of speckle noises. In this paper, an unsupervised distribution-free change detection for SAR image based on scale-invariant feature transform (SIFT) keypoints and segmentation is proposed. Firstly, the noise-robust SIFT keypoints which reveal the blob-like structures in an image are extracted in the log-ratio image to reduce the detection range. Then, different from the traditional change detection which directly obtains the change-detection map from the difference image, segmentation is made around the extracted keypoints in the two original multitemporal SAR images to obtain accurate changed region. At last, the change-detection map is generated by comparing the two segmentations. Experimental results on the real SAR image dataset demonstrate the effectiveness of the proposed method.
Time-Frequency Feature Extraction Method Based on Micro-Doppler Signature of Ground Moving Targets
Since some discriminative features are required for ground moving targets classification, we propose a new feature extraction method based on micro-Doppler signature. Firstly, the time-frequency analysis of measured data indicates that the time-frequency spectrograms of the three kinds of ground moving targets, i.e., single walking person, two people walking and a moving wheeled vehicle, are discriminative. Then, a three-dimensional time-frequency feature vector is extracted from the time-frequency spectrograms to depict these differences. At last, a Support Vector Machine (SVM) classifier is trained with the proposed three-dimensional feature vector. The classification accuracy to categorize ground moving targets into the three kinds of the measured data is found to be over 96%, which demonstrates the good discriminative ability of the proposed micro-Doppler feature.
An Image Segmentation Algorithm for Gradient Target Based on Mean-Shift and Dictionary Learning
In electromagnetic imaging, because of the diffraction limited system, the pixel values could change slowly near the edge of the image targets and they also change with the location in the same target. Using traditional digital image segmentation method to segment electromagnetic gradient images could bring lots of errors because of this change in pixel values. To address this issue, this paper proposes a novel image segmentation and extraction algorithm based on Mean-Shift and dictionary learning. Firstly, the preliminary segmentation results from adaptive bandwidth Mean-Shift algorithm are expanded, merged and extracted. Then the overlap rate of extracted image block is detected before determining a segmentation region with single complete target. Last, the gradient edge of extracted targets is recovered and reconstructed by using dictionary-learning algorithm while the final segmentation results are obtained which are very close to the gradient target in the original image. Both the Experimental results and the simulated results show that the segmentation results are very accurate. The Dice coefficients are improved by 70% to 80% compared with Mean-Shift only method.
Electromagnetic Source Direction of Arrival Estimation via Virtual Antenna Array
Nowadays, due to diverse electric products and complex electromagnetic environment, the localization and troubleshooting of the electromagnetic radiation source is urgent and necessary especially on the condition of far field. However, based on existing direction of arrival (DOA) positioning method, the system or devices are complex, bulky and expensive. To address this issue, this paper proposes a single antenna radiation source localization method. A single antenna moves to form a virtual antenna array combined with DOA and MUSIC algorithm to positioning accurately meanwhile reduce the cost and simply the equipment. As shown in the results of simulations and experiments, the virtual antenna array DOA estimation modeling is correct and its positioning is credible.
Compressed Sensing-Based Directions of Arrival and Directions of Departure Estimation in Bistatic Co-Prime Multi-Input and Multi-Output Arrays
In this paper, the bistatic co-prime multi-input and multi-output (MIMO) arrays are considered. With multiple far field targets, both the directions of departure (DODs) and the directions of arrival (DOAs) are estimated. By exploiting the larger virtual array aperture, the better estimation performance can be achieved in the co-prime MIMO arrays. Additionally, since the targets are sparse in the detection area, the compressed sensing (CS)-based method is proposed to reconstruct the sparse vector and obtain the target positions. Moreover, the theoretical Cram´er-Rao lower bound (CRLB) is also theoretical derived to describe the estimation performance in the bistatic co-prime MIMO arrays. Simulation results show that the better estimation performance can be achieved by the bistatic co-prime MIMO arrays than that by the traditional uniform linear arrays (ULA).
A Real-Time Moving Object Detection and Tracking Scheme and Its Implementation for Video Surveillance System
Detection and tracking of moving objects are very important in many application contexts such as detection and recognition of people, visual surveillance and automatic generation of video effect and so on. However, the task of detecting a real shape of an object in motion becomes tricky due to various challenges like dynamic scene changes, presence of shadow, and illumination variations due to light switch. For such systems, once the moving object is detected, tracking is also a crucial step for those applications that used in military defense, video surveillance, human computer interaction, and medical diagnostics as well as in commercial fields such as video games. In this paper, an object presents in dynamic background is detected using adaptive mixture of Gaussian based analysis of the video sequences. Then the detected moving object is tracked using the region based moving object tracking and inter-frame differential mechanisms to address the partial overlapping and occlusion problems. Firstly, the detection algorithm effectively detects and extracts the moving object target by enhancing and post processing morphological operations. Secondly, the extracted object uses region based moving object tracking and inter-frame difference to improve the tracking speed of real-time moving objects in different video frames. Finally, the plotting method was applied to detect the moving objects effectively and describes the object’s motion being tracked. The experiment has been performed on image sequences acquired both indoor and outdoor environments and one stationary and web camera has been used.
Design and Simulation of an Inter-Satellite Optical Wireless Communication System Using Diversity Techniques
In this reign of the internet, the access of any multimedia file to the users at any time with a superior quality is needed. To achieve this goal, it is very important to have a good network without any interruptions between the satellites along with various earth stations. For that purpose, a high speed inter-satellite optical wireless communication system (IsOWC) is designed with space and polarization diversity techniques. IsOWC offers a high bandwidth, small size, less power requirement and affordable when compared with the present microwave satellite systems. To improve the efficiency and to reduce the propagation delay, inter-satellite link is established between the satellites. High accurate tracking systems are required to establish the reliable connection between the satellites as they have their own orbits. The only disadvantage of this IsOWC system is laser beam width is narrower than the RF because of this highly accurate tracking system to meet this requirement. The satellite uses the 'ephemerides data' for rough pointing and tracking system for fine pointing to the other satellite. In this proposed IsOWC system, laser light is used as a wireless connectedness between the source and destination and free space acts as the channel to carry the message. The proposed system will be designed, simulated and analyzed for 6000km with an improvement of data rate over previously existing systems. The performance parameters of the system are Q-factor, eye opening, bit error rate, etc., The proposed system for Inter-satellite Optical Wireless Communication System Design Using Diversity Techniques finds huge scope of applications in future generation communication purposes.
Hand Motion and Gesture Control of Laboratory Test Equipment Using the Leap Motion Controller
In this paper, the design and development of a system to provide hand motion and gesture control of laboratory test equipment is considered and discussed. The Leap Motion controller is used to provide an input to control a laboratory power supply as part of an electronic circuit experiment. By suitable hand motions and gestures, control of the power supply is provided remotely and without the need to physically touch the equipment used. As such, it provides an alternative manner in which to control electronic equipment via a PC and is considered here within the field of human computer interaction (HCI).