Source Module Research Articles

A Control System Based on Microprocessor and FPGA for 1470nm High-power Semiconductor Laser

An intelligent control system for a medical high-power semiconductor laser has been developed. The system combines 1470nm high-power semiconductor laser and intelligent control technology. The control technique applies an ARM Cortex-M3 microprocessor STM32F103 as the core, an FPGA to drive the digital constant current source module and the power feedback loop to realize constant power control. Furthermore, the display and storage of the output data, and the driver of the touch screen are realized by designing the main control module and human-computer interaction module with the microprocessor. Finally, the Micro-Controller Development Kit (MDK) platform is used for programming. The safety performance of the whole control system conforms to the national standard of medical electrical safety.

AkvaGIS: An open source tool for water quantity and quality management

AkvaGIS is a novel, free and open source module included in the FREEWAT plugin for QGIS that supplies a standardized and easy-to-use workflow for the storage, management, visualization and analysis of hydrochemical and hydrogeological data. The main application is devised to simplify the characterization of groundwater bodies for the purpose of building rigorous and data-based environmental conceptual models (as required in Europe by the Water Framework Directive). For data-based groundwater management, AkvaGIS can be used to prepare input files for most groundwater flow numerical models in all of the available formats in QGIS. AkvaGIS is applied in the Walloon Region (Belgium) to demonstrate its functionalities. The results support a better understanding of the hydrochemical relationship among aquifers in the region and can be used as a baseline for the development of new analyses, e.g., further delineation of nitrate vulnerable zones and management of the monitoring network to control chemical spatial and temporal evolution. AkvaGIS can be expanded and adapted for further environmental applications as the FREEWAT community grows.

Using Integrated Environmental Modeling to Assess Sources of Microbial Contamination in Mixed-Use Watersheds.

Microbial fate and transport in watersheds should include a microbial source apportionment analysis that estimates the importance of each source, relative to each other and in combination, by capturing their impacts spatially and temporally under various scenarios. A loosely configured software infrastructure was used in microbial source-to-receptor modeling by focusing on animal- and human-impacted mixed-use watersheds. Components include data collection software, a microbial source module that determines loading rates from different sources, a watershed model, an inverse model for calibrating flows and microbial densities, tabular and graphical viewers, software to convert output to different formats, and a model for calculating risk from pathogen exposure. The system automates, as much as possible, the manual process of accessing and retrieving data and completes input data files of the models. The workflow considers land-applied manure from domestic animals on undeveloped areas; direct shedding (excretion) on undeveloped lands by domestic animals and wildlife; pastureland, cropland, forest, and urban or engineered areas; sources that directly release to streams from leaking septic systems; and shedding by domestic animals directly to streams. The infrastructure also considers point sources from regulated discharges. An application is presented on a real-world watershed and helps answer questions such as: What are the major microbial sources? What practices contribute to contamination at the receptor location? What land-use types influence contamination at the receptor location? and Under what conditions do these sources manifest themselves? This research aims to improve our understanding of processes related to pathogen and indicator dynamics in mixed-use watershed systems.

A Recommended Cascaded Structure for Multilevel Inverter with Minimum Power Electronic Components

Multi-level inverters (MLIs) are the best choice for medium and higher power applications. As the requirement of switches is more for higher levels, its cost and space are high in comparison with two-level inverters. A new structure for sub multi-level inverter (sub-MLI) is proposed with single source module and double source module to reduce power electronic components such as power switches, diodes, and drivers. The recommended cascaded structure is formed by connecting basic sub-MLI units in series to achieve minimum blocking voltage with less cost. In order to increase the voltage levels, the asymmetric topologies with different DC voltage values are also suggested. In addition, an optimal structure is arrived and compared with the conventional topologies to explore its advantages. It is found that the components, blocking voltage, and inverter cost are less. The proposed recommended cascaded structure is designed and analyzed for both symmetric and asymmetric configurations. The prototype is developed and performance of the inverter is experimentally verified for 13 and 31 level outputs.

Open source modules for tracking animal behavior and closed-loop stimulation based on Open Ephys and Bonsai

Objective. A major goal in systems neuroscience is to determine the causal relationship between neural activity and behavior. To this end, methods that combine monitoring neural activity, behavioral tracking, and targeted manipulation of neurons in closed-loop are powerful tools. However, commercial systems that allow these types of experiments are usually expensive and rely on non-standardized data formats and proprietary software which may hinder user-modifications for specific needs. In order to promote reproducibility and data-sharing in science, transparent software and standardized data formats are an advantage. Here, we present an open source, low-cost, adaptable, and easy to set-up system for combined behavioral tracking, electrophysiology, and closed-loop stimulation. Approach. Based on the Open Ephys system (www.open-ephys.org) we developed multiple modules to include real-time tracking and behavior-based closed-loop stimulation. We describe the equipment and provide a step-by-step guide to set up the system. Combining the open source software Bonsai (bonsai-rx.org) for analyzing camera images in real time with the newly developed modules in Open Ephys, we acquire position information, visualize tracking, and perform tracking-based closed-loop stimulation experiments. To analyze the acquired data we provide an open source file reading package in Python. Main results. The system robustly visualizes real-time tracking and reliably recovers tracking information recorded from a range of sampling frequencies (30–1000 Hz). We combined electrophysiology with the newly-developed tracking modules in Open Ephys to record place cell and grid cell activity in the hippocampus and in the medial entorhinal cortex, respectively. Moreover, we present a case in which we used the system for closed-loop optogenetic stimulation of entorhinal grid cells. Significance. Expanding the Open Ephys system to include animal tracking and behavior-based closed-loop stimulation extends the availability of high-quality, low-cost experimental setup within standardized data formats serving the neuroscience community.

Optical design of a high-mast luminaire based on four COB LED light source modules

Light-emitting diodes (LEDs) have been widely used in road lighting. This study investigates the optical design of a high-mast luminaire based on four chips-on-board LED light source modules and applies it to road lighting. The model of the high-mast luminaire is built with Solidworks, and then the optical simulations are analysed by Tracepro and Dialux. We also make a physical prototype of the high-mast luminaire to test its performance in practice. The illuminance distribution of the test area is nearly rectangular. The interior of the rectangle forms a smaller highlighted rectangular illumination area with uniform illumination. The outer edges of the rectangular illumination area will overlap the outer edges of the illumination area of other high-mast luminaires. The desired illuminance distribution and the uniform illumination can be obtained. Both the simulations and the experimental results meet the requirements of road lighting standards and the high-mast lamp can even achieve a better optical performance.

Wide-band white light sparse-aperture Fizeau imaging interferometer testbed for a distributed small-satellites constellation.

Under the background of astronomical observation by a distributed small-satellites constellation, a Fizeau imaging interferometer testbed (FIIT) was designed and constructed at National Astronomical Observatories of the Chinese Academy of Sciences in the past four years that achieved wide-band white light (400-700nm) phased imaging at laboratory with a field of view (FOV) ∼2 arcmin. This study presents the design of FIIT, which is mainly composed of a light source module for simulating infinite objects, three sub-telescopes in a Golay-3 distribution (i.e., equilateral triangle), three tip/tilt correction modules and optical path delay modules, as well as three detecting telescopes and one beam-combining telescope for phased imaging. The three detecting telescopes could determine the piston and tip/tilt errors, which could be compensated for by optical path delay modules and fast steering mirrors in a close-loop mode. The performance of FIIT is also derived analytically and simulated by a ray-tracing model. The tolerance analysis of the pupil geometry and magnification matching are also performed for achieving a better FOV. The optical test of each module could efficiently validate them to achieve diffraction limit imaging. The preliminary experimental results for both point source and extend scene could sufficiently demonstrate the phased mode imaging of FIIT, thus validating the good prospects of this technique in the future.

The shift orbits of the graded Kronecker modules

The Kronecker modules (or matrix pencils) are the representations of the n-Kronecker quiver K(n) (the quiver with two vertices, namely a sink and a source, and n arrows) over some fixed field. The universal cover of K(n) is the n-regular tree with bipartite orientation. The paper deals with the representations of the n-regular tree with bipartite orientation (thus with graded Kronecker modules). The simultaneous Bernstein-Gelfand-Ponomarev reflection at all sinks will be called the shift functor, and we consider the orbits under this shift functor. Whereas the length of a regular module growths exponentially when we apply the shift functor repeatedly, the radius of such a module growths just linearly. To any regular shift orbit, we attach a positive integer r (the minimal radius of the sink modules in the orbit) and the path in T(n) which starts at the center p of the sink modules in the orbit and ends at the center q of the source modules in the orbit. If r is even, then p has to be a sink, otherwise a source. We call this path the center path of the orbit (since the center of any module in the orbit lies on this path). If the center path of a shift orbit has length b, then the orbit contains precisely b flow modules, the remaining modules are sink modules and source modules. We use this division in order to index the regular graded Kronecker modules in a coherent way. Conversely, we show that given a positive integer r and a path in T(n) (starting at a sink iff r is even), there are regular shift orbits with these invariants.

Pattern-projected schlieren imaging method using a diffractive optics element

We propose a novel schlieren imaging method by projecting a random dot pattern, which is generated in a light source module that includes a diffractive optical element. All apparatuses are located in the source side, which leads to one-body sensor applications. This pattern is distorted by the deflections of schlieren objects such that the displacement vectors of random dots in the pixels can be obtained using the particle image velocity algorithm. The air turbulences induced by a burning candle, boiling pot, heater, and gas torch were successfully imaged, and it was shown that imaging up to a size of 0.7 m × 0.57 m is possible. An algorithm to correct the non-uniform sensitivity according to the position of a schlieren object was analytically derived. This algorithm was applied to schlieren images of lenses. Comparing the corrected versions to the original schlieren images, we showed a corrected uniform sensitivity of 14.15 times on average.

Phase-shifting interference microscope with extendable field of measurement

An innovative phase-shifting interference microscope aimed at extending the field of measurement is proposed in this paper. The microscope comprises a light source module, a phase modulation module, and an interferometric module, which reconstructs the micro-structure contours of samples using the five-step phase-shifting algorithm. This paper discusses the measurement theory and outlines the configuration, experimental setup, and experimental results obtained using the proposed interference microscope. The results confirm the efficacy of the microscope, achieving a standard deviation of 2.4 nm from a step height of 86.2 nm in multiple examinations.

A policy‐centric approach to protecting OS kernel from vulnerable LKMs

SummaryLoadable kernel modules (LKMs) that contain vulnerabilities are a big threat to modern operating systems (OSs). The primary reason is that there is no protection mechanism inside the kernel space when the LKM is executed. As a result, kernel module exploitation can seriously affect the OS kernel security. Although many protection systems have been developed to address this problem in the past few years, there still remain some challenges: (1) How to automatically generate a security policy before the kernel module is enforced? (2) How to properly mediate the interactions between the kernel module and the OS kernel without modifications on the existing OS, hardware, and kernel module structure? To address these challenges, we present LKM guard (LKMG), a policy‐centric system that can protect commodity OS kernel from vulnerable LKMs. Compared with previous systems, LKMG is able to generate a security policy from a kernel module and then enforce the policy during the run time. Generally, the working process of LKMG can be divided into 2 stages. First, we utilize static analysis to extract the kernel code and data access patterns from a kernel module's source code and then combine these patterns with the related memory address information to generate a security policy. Second, by leveraging the hardware‐assisted virtualization technology, LKMG isolates the kernel module from the rest of the kernel and then enforces the kernel module's execution to obey the derived policy. The experiments show that our system can defend against various attacks launched by the compromised kernel module effectively with moderate performance cost.

Estimation of sound speed and attenuation in muddy sediments using spatial coherence measurements of sound propagation

In the spring of 2017, a multi-national and multi-institute shallow water propagation experiment was conducted in the New England Mud Patch in order to study the acoustic properties in muddy sediments. Different types of acoustic signals (i.e., 31-g explosive charges, combustive sound source, multi-tone, and linear frequency modulation signals) deployed at various ranges, depths and azimuths were measured by one L-shaped array, one horizontal line array, and several vertical line arrays within the 30 km × 10 km experimental area. In this paper, these measured signals are first utilized to obtain the correlation coefficients for vertical coherence (VC) and longitudinal horizontal coherence (LHC), which are sensitive to the seabed geo-acoustic parameters. These spatial coherence measurements are then applied in the VC and LHC based geo-acoustic inversion algorithms [Wan et. al. JASA, 2016] to infer sound speed and attenuation in muddy sediments. Finally, the results from VC and LHC based geo-acoustic invers...

Time Resolved Diffuse Optical Tomography model

Time Resolved Diffuse Optical Tomography (TRDOT) modality is presented. Images were reconstructed for four different scenarios. 64-source and 64-detector bifurcated positions were used for simulation model. Inclusion was buried in different coordinate locations. Time-dependent diffusion equation for photon-tissue interactions were used to create the forward model. Mostly used TRDOT devices have pulsed-laser source and photo-multiplier tube (PMT) photodetectors. In addition to pulsed laser source, continuous wave (CW) sources would be used for TRDOT imaging. In general usage, solid-state diode pumped pulsed-lasers and driving units constitute source module. Solid-state lasers are made of Titanium Sapphire (TiSa). These laser sources are difficult to use, modify, maintain, and they are also expensive. Instead of using expensive pulsed laser sources, cheap electronic-based pulsed-laser driving circuit will be implemented. Pseudomorphic high electron mobility transistors (pHEMTs) as switching elements will be used at both pulsed-laser and photodiode current readout sides. Hence, this work is taking its motivation from the next-generation electronic-based device instrument, creating the time dependent forward model as its focus. In this work, it was seen that selection of time intervals are important parameters to reconstruct the hidden images inside the homogeneous tissue. Inclusion was buried inside the homogeneous tissue model, and corresponding time modes have been selected to extract the hidden inclusion. In this work, time modes were analyzed for the TRDOT device. It has been realized that different time mode forward model weight functions should be used for different depth layers to reconstruct the hidden inclusion correctly. Hence, different time mode forward model weight matrix functions were generated from time 20 ps to 400 ps by 20 ps steps, and from time 2 ps to 40 ps by 2 ps steps. In the mathematical inverse problem solution algorithm, these time clusters were used to create two different weight matrixes.

Benchtop and animal validation of a portable fluorescence microscopic imaging system for potential use in cholecystectomy

We propose a portable fluorescence microscopic imaging system (PFMS) for intraoperative display of biliary structure and prevention of iatrogenic injuries during cholecystectomy. The system consists of a light source module, a camera module, and a Raspberry Pi computer with an LCD. Indocyanine green (ICG) is used as a fluorescent contrast agent for experimental validation of the system. Fluorescence intensities of the ICG aqueous solution at different concentration levels are acquired by our PFMS and compared with those of a commercial Xenogen IVIS system. We study the fluorescence detection depth by superposing different thicknesses of chicken breast on an ICG-loaded agar phantom. We verify the technical feasibility for identifying potential iatrogenic injury in cholecystectomy using a rat model in vivo. The proposed PFMS system is portable, inexpensive, and suitable for deployment in resource-limited settings.

Design of Electromagnetic Tracking System Using Rotating Magnetic Field Based on DSP

This paper realized an electromagnetic tracking system based on electrically-controlled rotating magnetic field. A tracking system using the digital signal processor (DSP) as the control processing device was developed, including a controllable constant current source module, a magnetic field source module, a three-axis magnetic sensor and ADC interface circuit. The experimental results verified that each time the system could be stable positioning, average error of position was 0.282 cm, the average error of orientation was 0.696o, the positioning time was 1.572 s. Through calibration and further improvement of the hardware circuit, the performance of the system is expected to further improve.

FPGA-Based Solutions for Analog Data Acquisition and Processing Integrated in Area Detector Using FlexRIO Technology

Analog data acquisition systems used for diagnostics and control of large physics experiments require high sampling rates and real-time processing functionalities. The use of field-programmable gate array (FPGA)-based devices allows efficient implementation of such solutions. Currently, large scientific facilities are using middleware platforms to simplify system integration. Experimental physics and industrial control system (EPICS) is one of the most popular middleware for this purpose. Moreover, heterogeneous hardware integration in these systems is a very complex task, and different approaches attempting to standardize this integration are under development and use. One of these approaches is areaDetector (AD), which involves an open source module for EPICS that is primarily used for image acquisition applications. AD simplifies the integration of heterogeneous image acquisition systems, providing a common interface between the hardware and EPICS. The AD community has already developed support for different cameras and communication protocols as well as different processing modules, including conversion to the most commonly used image formats. AD has also been used in some analog signal acquisition systems; for example, quadEM is typically used for a photodiode-based X-ray beam, but there are no implementations based on FPGA, such as FlexRIO technology. This paper presents the integration of acquisition and processing solution in a PXIe platform using the FlexRIO technology using a model that solves the acquisition and signal processing in an FPGA and a software layer implemented in C++ with the IRIO library (open source solution for RIO devices in the Linux environment).

Modulus design multiwavelength polarization microscope for transmission Mueller matrix imaging.

We have developed a polarization microscope based on a commercial transmission microscope. We replace the halogen light source by a collimated LED light source module of six different colors. We use achromatic polarized optical elements that can cover the six different wavelength ranges in the polarization state generator (PSG) and polarization state analyzer (PSA) modules. The dual-rotating wave plate method is used to measure the Mueller matrix of samples, which requires the simultaneous rotation of the two quarter-wave plates in both PSG and PSA at certain angular steps. A scientific CCD detector is used as the image receiving module. A LabView-based software is developed to control the rotation angels of the wave plates and the exposure time of the detector to allow the system to run fully automatically in preprogrammed schedules. Standard samples, such as air, polarizers, and quarter-wave plates, are used to calibrate the intrinsic Mueller matrix of optical components, such as the objectives, using the eigenvalue calibration method. Errors due to the images walk-off in the PSA are studied. Errors in the Mueller matrices are below 0.01 using air and polarizer as standard samples. Data analysis based on Mueller matrix transformation and Mueller matrix polarization decomposition is used to demonstrate the potential application of this microscope in pathological diagnosis.

Spatial modulation of laser sources for microstructural control of additively manufactured metals

Metal powder-bed fusion additive manufacturing (AM), while demonstrating great potential across a diverse application space, still lacks the necessary control to obtain parts that meet strict performance-driven criteria. In this work, we explore spatial laser modulation to enhance the properties and processability of AM metals. Experiments are carried out with the goals of demonstrating control of the columnar-to-equiaxed transition, identify methods to reduce surface roughness, and extend processing windows for AM alloys. Results show that beam modulation provides site-specific microstructural control, and these results are interpreted using finite element modeling of the melt pool dynamics and thermal profiles.

Focus Tracking using a 1 ms 3D Feedback Microscope based on High-speed Modulation of Light Sources

Focus Tracking using a 1 ms 3D Feedback Microscope based on High-speed Modulation of Light Sources

Precise Forecast and Application of Time Delay Receiving Schedule for a New Generation of Polar Orbit Meteorological Satellite

In order to finely predict the receiving schedule of the new generation of polar orbit meteorological satellite time-delay data and solve the problem of rapid positioning of lost data, this paper studies and proposes the satellite data recording and satellite program-controlled program, and designs the delay data receiving timeline precision forecasting method. It is concluded that the detection load of polar orbit meteorological satellite in our country has developed from single load to multiple loads, and the detection data need to be downloaded to the ground for processing and application. And as the satellite load increases and the accuracy of each payload detection and channel increases, the amount of probing data will further increase, which in turn will require further increase of the speed of data transmission in the earth. Due to the limitation of the space data transmission frequency band, under the prior art system, the increase of the satellite data transmission rate is limited. On the basis of understanding the working principle of Fengyun-3, the new transmission system will be implemented in terms of data source compression, channel coding, modulation and polarization multiplexing by exploring new weather transmission systems for meteorological satellites in the future upgrade and at the same time analyze ways to avoid inter-satellite interference in order to solve the contradiction between the increase of data volume and the resource of terrestrial data transmission in the existing system.