Input Phase Research Articles

Determining Reliability Requirements and Testing Costs in the Early Stages of Single Use Medical Product Design

ABSTRACTThe production of single use medical devices, particularly for home use by patients, continues to grow, and the reliability of these devices is a primary concern for manufacturers and end‐users. The systems engineer tasked with the device development needs methods and tools to establish reliability requirements and provide cost estimates for the testing necessary to show compliance with those requirements. This paper examines methods for determining reliability requirements, the cost of reliability testing for single use medical devices in the design input phase of product development, and how the costs of testing and potential errors can be used to perform trade‐off analysis between reliability tolerance and confidence level.

Design of a Dual-Input Dual-Output Power Amplifier With Flexible Power Allocation

While dual-output power amplifiers (PAs) have shown great potential in the area of radar, satellite, and wireless communication systems, the flexibility of the power allocation in the dual-output PAs should be improved without sacrificing efficiency and circuit complexity. This letter presents a dual-input dual-output (DIDO) PA to enable flexible power allocation based on a simple circuit topology. It is demonstrated that not only power transfer from one output port to the other, but also flexible power allocation between two output ports can be obtained by the proposed DIDO PA. Meanwhile, optimal drain efficiency (DE) can be maintained when different power is delivered to the two output ports of the DIDO PA by controlling the input conditions. As a proof of concept, a DIDO PA operating at 2.4 GHz is fabricated and measured in this letter. The fabricated DIDO PA could deliver a total output power of more than 44 dBm and the total power can be allocated between two output ports. The maximum DE of the DIDO PA ranges from 71.8% to 75.6% over the 360° input phase difference.

Reconstructed Phase Voltages Based Power Following Control for Three-Phase Buck Rectifier Under Unbalanced Phase Voltages and Wide AC Input Frequency

In wide ac input frequency applications, such as more electric aircraft, ac input frequency of the three-phase buck rectifier varies in the range of 360–800 Hz. In this article, a reconstructed phase voltages based power following control for the three-phase buck rectifier under unbalanced input phase voltages in wide ac input frequency application is proposed. The input phase voltages are reconstructed to get more balanced modulation signals compared with the input phase voltages. The input currents are controlled to be in proportion to the reconstructed phase voltages to mitigate the imbalance of the input currents. The control strategy is simple and easy to be realized in digital. The analysis and design of the proposed control strategy and digital implementation are illustrated. An experimental prototype with 1.5 kW is built. The experimental results show that the sinusoidal input currents can be obtained when input phase voltages are unbalanced in wide ac input frequency application.

On-Line Condition Monitoring System for DC-Link Capacitor of Back-to-Back Converters Using Large-Signal Transients

The increasing use of power electronic equipment and the importance of their continuous and correct operation have attracted remarkable attention to the condition monitoring of power electronic converters. Since capacitors are the leading cause of power electronic converters failure, this article attempts to attain a solution to monitor the condition of the dc-link capacitor in a three-phase back-to-back converter using the stimulated measurable transients. The proposed method works based on the temporary change of switching logic and the measurement of the dc-link voltage and converter input phase current transients. By processing the measured signals, the capacitance of the capacitor is calculated as an indicator of its degradation. The results of simulations and experimental studies are presented to verify the proficiency of the proposed method. Based on the results, the calculated capacitance is consistent with the value measured by an LCR meter with an estimation error of less than 1%.

Artificial confocal microscopy for deep label-free imaging.

Widefield microscopy of optically thick specimens typically features reduced contrast due to "spatial crosstalk", in which the signal at each point in the field of view is the result of a superposition from neighbouring points that are simultaneously illuminated. In 1955, Marvin Minsky proposed confocal microscopy as a solution to this problem. Today, laser scanning confocal fluorescence microscopy is broadly used due to its high depth resolution and sensitivity, but comes at the price of photobleaching, chemical, and photo-toxicity. Here, we present artificial confocal microscopy (ACM) to achieve confocal-level depth sectioning, sensitivity, and chemical specificity, on unlabeled specimens, nondestructively. We equipped a commercial laser scanning confocal instrument with a quantitative phase imaging module, which provides optical path-length maps of the specimen in the same field of view as the fluorescence channel. Using pairs of phase and fluorescence images, we trained a convolution neural network to translate the former into the latter. The training to infer a new tag is very practical as the input and ground truth data are intrinsically registered, and the data acquisition is automated. The ACM images present significantly stronger depth sectioning than the input (phase) images, enabling us to recover confocal-like tomographic volumes of microspheres, hippocampal neurons in culture, and 3D liver cancer spheroids. By training on nucleus-specific tags, ACM allows for segmenting individual nuclei within dense spheroids for both cell counting and volume measurements. In summary, ACM can provide quantitative, dynamic data, nondestructively from thick samples, while chemical specificity is recovered computationally.

Automated Control of Unauthorized Power Take-Offs in a Distributed Electrical Network

A distributed electrical network (DEN) with a voltage of 0.4 kV operating in an unsymmetric mode is considered as an object of automated control. The problem of identification of places and control of unauthorized power take-offs (UPTO) in the DEN in the conditions of functioning of the automated system of control and accounting of electricity (ACMSE) is formulated. The primary source information for its solution is the data obtained from the head and subscriber electricity meters by synchronized remote measurements at discrete points in time. This problem belongs to the class of problems in which there is significant uncertainty about the current state of the object under study and the parameters of external disturbing influences, which are unauthorized consumers of electricity. Under these conditions, the primary measurement data on the characteristics of the network subscribers’ loads received from the counters of the automated system and recorded in its database are insufficient to solve the problem under consideration. In this regard, in order to reduce the level of uncertainty and obtain additional necessary information about the state of the object, the concept of a virtual DEN model is introduced into consideration, designed to describe its desired state, which is determined by the absence of these external random disturbances in the network. A new method for solving the formulated problem is proposed, based on the concept of a virtual DEN model. The conditions for identifying the current state of the DEN have been obtained. For this purpose, the desired input phase currents of the virtual network are determined by introducing equivalent complex resistances of certain parts of the three-phase network. The vectors of the effective values of currents and voltages on the loads of subscribers and inter-subscriber sections of the virtual network are identified. Criterion functions are introduced that determine the deviations of the corresponding components of the stress vectors on the loads of subscribers of the real DEN and its virtual model. Based on these functions, an identification criterion and an algorithm for monitoring unauthorized power take-offs in a three-phase distributed network are formulated. The obtained results are oriented for the creation of algorithmic and special software for the subsystem of automated control of UPTO as part of the ACMSE.

Fault Identification and Localization of a Time−Frequency Domain Joint Impedance Spectrum of Cables Based on Deep Belief Networks

To improve the accuracy of shallow neural networks in processing complex signals and cable fault diagnosis, and to overcome the shortage of manual dependency and cable fault feature extraction, a deep learning method is introduced, and a time-frequency domain joint impedance spectrum is proposed for cable fault identification and localization based on a deep belief network (DBN). Firstly, based on the distribution parameter model of power cables, we model and analyze the cables under normal operation and different fault types, and we obtain the headend input impedance spectrum and the headend input time-frequency domain impedance spectrum of cables under various operating conditions. The headend input impedance amplitude and phase of normal operation and different fault cables are extracted as the original input samples of the cable fault type identification model; the real part of the headend input time-frequency domain impedance of the fault cables is extracted as the original input samples of the cable fault location model. Then, the unsupervised pre-training and supervised inverse fine-tuning methods are used for automatically learning, training, and extracting the cable fault state features from the original input samples, and the DBN-based cable fault type recognition model and location model are constructed and used to realize the type recognition and location of cable faults. Finally, the proposed method is validated by simulation, and the results show that the method has good fault feature extraction capability and high fault type recognition and localization accuracy.

Rotor Noise-Aware Noise Covariance Matrix Estimation for Unmanned Aerial Vehicle Audition

A noise covariance matrix (NCM) estimation method for unmanned aerial vehicle (UAV) audition is proposed with rotor noise reduction as its primary focus. The proposed NCM estimation method could be incorporated into audio processing algorithms using UAV-mounted microphone array systems. The NCM is formed through accurate estimation of the microphone array input signal's amplitude and phase by using a multi-sensory rotor noise power spectral density (PSD) estimator and a filter formed by exploiting the acoustical relationship between the microphone array and the rotor noise sources, respectively. The estimated NCM aims to be readily incorporable into several source enhancement algorithms to reduce the effects of rotor noise and improve the resultant audio quality. Experiment evaluation using real in-flight UAV rotor noise recordings shows that the estimated NCM significantly improves rotor noise reduction (of up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 28$</tex-math></inline-formula> dB) and the quality of the target sound.

Analysis, Design, and Optimization of the IPT System With LC Filter Rectifier Featuring High Efficiency

Passive diode bridge rectifier with LC filter is widely used in wireless power transfer (WPT) system due to its simple structure and uncontrolled characteristics. However, as the load resistance decreases, its input phase angle will also decrease rapidly until it shows obvious capacitive. Therefore, a novel rectifier topology with an input-series inductor (hereafter called ISIR) is proposed in this article to solve this problem. What is more, the ISIR can avoid the duty cycle loss and improve the dc–dc efficiency. First, the mechanism of ISIR is analyzed in detail combined with the operating status of topology. Then, the inductance and compensation parameters are determined based on theoretical calculation and simulation results. Finally, a prototype with a maximum load of 7 Ω is built to validate the feasibility and effectiveness of ISIR, and 88% efficiency is achieved under this condition. Compared with the traditional method, it has increased by 1.05%. The maximum efficiency of WPT system is as high as 91.14% with the proposed ISIR.

Photonic Generation of a Windowed Phase-Coded Microwave Waveform With Suppressed Spectrum Sidelobes

An approach to photonic generation of a windowed binary phase-coded microwave waveform with suppressed spectrum sidelobes is proposed and demonstrated. An optical double sideband plus carrier signal with the carrier and the two sidebands being orthogonally polarized is generated by a dual-polarization quadrature phase shift keying (DP-QPSK) modulator, with the generated signal sent to a phase modulator (PM) where phase coding is performed. The PM can support phase modulation in two orthogonal polarization directions. The phase-modulated signals are projected to one polarization direction and detected at a photodetector (PD). Switching the polarity of the coding signal, a π phase shift is introduced. Since the amplitude of the generated signal is dependent on the amplitude of the input coding signal, a windowing function is applied to the generated waveform by using a windowed input phase coding signal, to suppress the sidelobes in the spectrum of the generated microwave waveform. The key features of the proposed waveform generator include all-optical generation without the need of electronic components and optical filters, thus ensuring a wide operating frequency range. The proposed phase-coded microwave waveform generator also has the ability to switch between the fundamental and harmonic carrier frequency by controlling the modulator bias voltages. Experimental results show that, using a windowed 64-bit Gaussian pseudo-random binary sequence coding signal, a phase-coded microwave waveform is generated with the sidelobes of the spectrum largely suppressed by 20 dB and a pulse compression ratio as large as 133. Generation of binary phase-coded microwave waveforms at the 2nd harmonic carrier frequencies is also demonstrated experimentally.

Comparison between a rapid diagnostic test and dried blood spot-based immunoassay for hepatitis B surface antigen testing: Performance and cost implications in a population-based serosurvey in Vietnam

ObjectivesThis study aimed to determine the agreement between a rapid diagnostic test (RDT) and a dried blood spot (DBS)-based electrochemiluminescence immunoassay (ECLIA) of hepatitis B surface antigen and to compare the costs of conducting serosurveys using RDTs and DBS in a field setting. MethodsA serosurvey was conducted in the South Central Coast region of Vietnam in May 2019. Participants aged 1-39 years were recruited using a four-stage random sampling method and tested for hepatitis B surface antigen using an RDT kit (Alere Determine) and a DBS-based ECLIA. The agreement between the RDT and the DBS-based ECLIA was assessed using cross-tabulation and Cohen kappa. Cost data were categorized by input (personnel, transportation, field consumables, laboratory consumables, and capital item/overhead) and survey phase (survey preparation, data/biospecimen collection, laboratory testing, and coordination). ResultsA total of 2072 participants were analyzed. There was a 99% agreement between the RDT and the DBS-based ECLIA results, with a Cohen kappa of 0.9. The estimated cost of conducting a serosurvey by DBS was UD $75,291, whereas RDT was $53,182. ConclusionRDTs and DBS-based ECLIA provide test results with high agreements. RDTs are a better option in terms of cost, whereas the DBS-based ECLIA may be useful when evaluating multiple infectious diseases.

Causes of adverse events in home mechanical ventilation: a nursing perspective

BackgroundAdverse events (AE) are ubiquitous in home mechanical ventilation (HMV) and can jeopardise patient safety. One particular source of error is human interaction with life-sustaining medical devices, such as the ventilator. The objective is to understand these errors and to be able to take appropriate action. With a systematic analysis of the hazards associated with HMV and their causes, measures can be taken to prevent damage to patient health.MethodsA systematic adverse events analysis process was conducted to identify the causes of AE in intensive home care. The analysis process consisted of three steps. 1) An input phase consisting of an expert interview and a questionnaire. 2) Analysis and categorisation of the data into a root-cause diagram to help identify the causes of AE. 3) Derivation of risk mitigation measures to help avoid AE.ResultsThe nursing staff reported that patient transportation, suction and tracheostomy decannulation were the main factors that cause AE. They would welcome support measures such as checklists for care activities and a reminder function, for e.g. tube changes. Risk mitigation measures are given for many of the causes listed in the root-cause diagram. These include measures such as device and care competence, as well as improvements to be made by the equipment providers and manufacturers. The first step in addressing AE is transparency and an open approach to errors and near misses. A systematic error analysis can prevent patient harm through a preventive approach.ConclusionRisks in HMV were identified based on a qualitative approach. The collected data was systematically mapped onto a root-cause diagram. Using the root-cause diagram, some of the causes were analysed for risk mitigation. For manufacturers, caregivers and care services requirements for intervention offers the possibility to create a checklist for particularly risky care activities.

A Self-Powered P-SSHI Array Interface for Piezoelectric Energy Harvesters With Arbitrary Phase Difference

Piezoelectric energy harvester (PEH) arrays are promising in many application scenarios. However, few interface circuits have been developed to manage the multiple ac inputs from PEHs. This article proposes an extensible parallel synchronized switch harvesting on inductor array interface scheme to realize a multiinput conversion from PEH arrays. We develop a split-inductor-capacitor topology that can extract electrical energy from multiple PEHs. The proposed circuit topology effectively handles the inductor access conflict in the cases of PEHs with close, identical, and opposite vibration phases, insensitive to ac input phase changes. For demonstrating the capability of dealing with multiple ac inputs from PEHs and the enhancement effect on power output, we construct and test a self-powered three-channel array circuit with the passive peak detection function. Excited by sinusoidal vibrations, our circuit effectively avoids the energy return and efficiently achieves the power combination of the three PEHs. Compared with the classic full-bridge circuit, the proposed circuit helps increase the power output by 4.8 times. Also, to show the universality of the circuit, the circuit's operation under various excitations istested and analyzed.

Design and Application of Automatic Control System for Fully Mechanized Mining Face in Coal Mine

In order to improve the automatic control effect of fully mechanized mining face in coal mine, this paper combines the literature research method to analyze the disadvantages of traditional research and combines the demand analysis to analyze the structure of the automatic control system of fully mechanized mining face in coal mine. Moreover, this paper uses an improved algorithm to improve the system performance, uses the analytical approximation method to calculate and eliminate the loading phase of the fourth-order input and output equal-length cavity filter and the fourth-order input and output unequal-length cavity filter, and obtain the correct coupling matrix. In addition, this paper uses the genetic algorithm to calculate and eliminate the loading phase of the sixth-order input-output equal-length cavity filter and the sixth-order input-output unequal-length cavity filter. In addition, after the system is constructed, the performance analysis of the system can be known through experimental research. The research results show that the automatic control system of fully mechanized mining face in coal mine proposed in this paper has a good intelligent control effect.

Electric Vehicle Transient Speed Control Based on Vector Control FM-PI Speed Controller for Induction Motor

The speed control of induction machines for multiple-speed handling is critical. When the vector control method is applied to induction machines, it has a significant impact on speed utilization. This strategy of operating the machine at a fixed predefined speed mode presents better results for electric vehicles. An effective model for a speed control loop is proposed in this paper, using a fixed-mode proportional integral (FM-PI) controller based on an upper and lower limit torque limiter. The power supply is fed using a lithium-ion battery with an inverter-fed mechanism. Moreover, the proposed model is validated using simulations with user-defined speed modes (40, 60, and 80 km/h). These speed modes, with different torque commands, have been considered for advanced modeling. In this model, torque is developed via a closed-loop control operation to attain the required speed assigned by the user. The sensors are used to collect data, and a multiple regression algorithm analyzes the dataset to predict input parameters (voltage (Vab), phase current (I), and torque (T)) required to achieve the desired speed mode. The efficiency of the proposed model is compared with induction motors bearing the same rating for the loaded and unloaded speed test. Effective machine parameter control is achieved by reaching the desired performance levels of 94.37% and 78.30% in a shorter time for the loaded and unloaded modes. A speed response comparison of the FOPID, KW-WOA-PID, SVR-PI, and FM-PI controller model simulation results indicates that the FM-PI speed controller guarantees better performance and displays an improvement in rising time and settling time, compared to other controllers. The implementation of different driving scenarios proves the model’s effectiveness for robust speed applications.

Modeling the tonotopic map using a two-dimensional array of neural oscillators.

We present a model of a tonotopic map known as the Oscillatory Tonotopic Self-Organizing Map (OTSOM). It is a 2-dimensional, self-organizing array of Hopf oscillators, capable of performing a Fourier-like decomposition of the input signal. While the rows in the map encode the input phase, the columns encode frequency. Although Hopf oscillators exhibit resonance to a sinusoidal signal when there is a frequency match, there is no obvious way to also achieve phase tuning. We propose a simple method by which a pair of Hopf oscillators, unilaterally coupled through a coupling scheme termed as modified power coupling, can exhibit tuning to the phase offset of sinusoidal forcing input. The training of OTSOM is performed in 2 stages: while the frequency tuning is adapted in Stage 1, phase tuning is adapted in Stage 2. Earlier tonotopic map models have modeled frequency as an abstract parameter unconnected to any oscillation. By contrast, in OTSOM, frequency tuning emerges as a natural outcome of an underlying resonant process. The OTSOM model can possibly be regarded as an approximation of the tonotopic map found in the primary auditory cortices of mammals, particularly exemplified in the studies of echolocating bats.

Determination of alpha –alpha interaction from experiment

Fixed-energy quantum inversion method is applied to determine model independent alpha -particle scattering potentials within the energy range between 0 and 50 MeV. Only experimentally allowed even phase shifts are used in the calculation. Detailed results exhibited at low and higher energies show up a large interaction domain, a thin strong Pauli-blocking part and a smooth merging region between the colliding particles. Over-all agreement between input and re-calculated phase shifts justifies the procedure.

Prototype of high accuracy single input phase measurement instrument

A prototype implementation of a phase measurement method (PMM) for a sine-wave signal delivered at the output port of a generator and its experimental assessment is presented. This PMM is capable of measuring the output phase of a sine-wave signal respect to a reference phase with high accuracy and a very low uncertainty. A description of the prototype PMM, and its mathematical model are given in the paper. The prototype operates over the frequency range of 100Hz to 10MHz and it is composed from three main subsystems: (i) the sampling circuit, (ii) the pulse-train signal generator, and (iii) the data acquisition and digital signal processing. A laboratory test bench was realized to assess the phase measurement repeatability of the prototype, and a maximum phase standard deviation of 0.021° measured at 25°C was obtained for the output frequency of 10MHz, where the phase uncertainty decreases with decreasing frequency.

A DPWM Modulation Strategy to Reduce Common-Mode Voltage for Indirect Matrix Converters Based on Active-Current Vector Amplitude Characteristics

Based on the characteristics that the amplitude of active-current vector in the rectifier stage is zero when the zero-voltage vector is used in the inverter stage, and any one from the six active-current vectors can be selected, a novel discontinuous pulsewidth modulation (DPWM) strategy for the indirect matrix converter is proposed in this article to reduce the common-mode voltage (CMV). In this DPWM strategy, the reference current vector in the rectifier stage is synthesized by two adjacent active-current vectors, and the reference voltage vector in the inverter stage is synthesized by two adjacent active-voltage vectors and one zero-voltage vector. When zero-voltage vectors are used in the inverter stage, an appropriate active-current vector with the lowest input phase voltage among the two adjacent active-current vectors is used to produce a lower CMV. Under the same switching loss, the proposed strategy has a better input performance and better output performance in high voltage transfer ratio than conventional SVM. Finally, the effectiveness of the modulation strategy is verified by simulation and experiments.

Automatic Optimization of Input Split and Bias Voltage in Digitally Controlled Dual-Input Doherty RF PAs

Digitally controlled Dual-Input Doherty Power Amplifiers (DIDPAs) are becoming increasingly popular due to the flexible input signal splitting between the main and auxiliary stages. Nevertheless, the presence of many degrees of freedom, e.g., input amplitude split and phase displacement as well as biasing for multiple stages, often involves inefficient trial-and-error procedures to reach a suitable PA performance. This article presents automated parameter setting based on coordinate descent or Bayesian optimizations, demonstrating an improvement in the performance in terms of RF output power and power-added efficiency (PAE) in the presence of broadband-modulated signals, yet maintaining suitable linear behavior for, e.g., communications applications.