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With the increasing demand for large capacity power transmission over long distance, the use of overhead lines is required, which greatly increases the probability of temporary faults. After the faulty line is isolated by hybrid DC circuit breakers (HCBs), the power supply can be restored immediately by reclosing them in the event of temporary fault. However, fragile semiconductor switches will undergo two consecutive faults after the reclose of HCBs when permanent fault occurs. Therefore, a reclosing scheme is proposed in this paper to avoid the non-selective reclose of HCBs, whose core principle is an identification method of the instantaneous and the permanent faults. By controlling semiconductor switches in HCB, traveling wave signal is injected into the DC line. Then, whether the fault exists on the line can be determined by the difference in propagation characteristics of the injected signal. The effectiveness of the proposed reclosing scheme is verified by both point-to-point and four-terminal HVDC test systems based on modular multilevel converter built in PSCAD/EMTDC platform. Extensive simulations show that it is robust to fault resistance, etc., and has no identification dead zone. Besides, it has little impact on the healthy part of the system even the permanent fault occurs.

Predominantly, GPS-free localization algorithms are either predictive or probabilistic or range-dependent which outrage energy source and computing power of sensor-nodes. Whereas, comparatively less complex algorithms based on range-independent approaches find GPS-free approaches unfeasible due to their everlasting dependency on GPS like DV-Hop, etc. This gap motivates to propose RiL-DZ, an estimative range-independent absolute localization algorithm for GPS dead zone in mobile wireless sensor networks. RiL-DZ has two steps- ALE, and UL. In ALE, for the dead zone anchor-nodes calculate their location by measuring their respective distance and angular movement. Subsequently in UL, the absolute location of the unknown-nodes is attained by estimating their distances from the anchor-nodes of ALE step using hop parameters. Further, for precise localization, RiL-DZ considers errors in distance estimation between the node-pairs and the imprecise approximation of the location of anchor-nodes caused by error-affected displacement measurements. Furthermore, the error factors of distances calculated in between anchor-nodes and intended unknown-node are minimized using linear programming. The simulation shows RiL-DZ absorbs displacement error notably than other contenders and GPS-assisted DV-Hop throughout. The analysis-of-variance establishes that RiL-DZ depends significantly on communication range and anchor-nodes density only by 40.81% and 29.09% respectively.

The problem of the radar search-detection-classification of objects on the ground moving with random changes of the direction of the velocity vector is considered. A method for controlling the orientation of the radar beam, which maximizes the monitoring bandwidth on the Earth‘s surface, while providing the maximum possible resolution on it and the absence of “dead zones” to the left and right of the direction of movement of the objects, usually arising from the Doppler selection of the moving objects, is proposed. A computer model is created that allows us to study the dependence of the probabilities of detecting and classifying objects on the speed of their movement under various scenarios of monitoring by a massive numerical experiment. The advantages of the proposed method in comparison with traditional ones are proved by the modeling methods.

When a gravity-driven solid-fluid mixture, such as those in geophysical flows, hits a wall-like rigid obstacle, a metastable jammed zone called hydrodynamic dead zone (HDZ) may emerge. The unjammed-jammed transition of HDZ, controlled by the intricate interactions among the obstacle, the fluid and the solid of the flow, remains an open issue to be quantified for thorough understanding its underlying physics and mechanics. This study employs a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) to examine the characteristics of HDZ formed when a geophysical flow comprised of gap-graded particles and a viscous liquid impacts an obstacle. To identify key features in the zonation of HDZ, a modified granular temperature is proposed considering the influences of inherent polydispersity and both translational and rotational motions of the particles in the impacting mixture. A source-sink model is further established to offer an interpretation of the nonlinear energy dissipation process during the unjammed-jammed transition of HDZ, where the modified granular temperature serves as a function of either time or distance. The structural anisotropy is found to serve as a good indicator for illuminating the flow-structure interaction transitions. Three regimes, namely, impact-up, roll-up and heap-up regimes, have been identified according to the statistical energy conversion and dissipation in the flowing layer upon the HDZ. The influence of particle rotation is found to be more significant in the dynamical exchange of HDZ when the impacting flow contains a wider polydispersity. (c) 2021 Elsevier B.V. All rights reserved.

The emerging bottom blown copper smelting (SKS) technology has attracted growing interest since it came into production. To further reveal the agitation behavior inside the bath and optimize the variable parameters, CFD simulation was conducted on a scaled down SKS furnace model with different tuyere arrangements. The Multi-Fluid VOF model was used for the first time in SKS furnace simulation and the simulated results show good agreement with an experimental water model reported in the literature, in terms of plume shape and surface wave. It was found that a low velocity region would appear on the opposite side of the bubble plume and persisted for a long time. To enhance the agitation in the low velocity region and reduce the dead zone area, an arrangement with tuyeres installed at each side of the furnace was recommended. Results suggested that a smaller tuyere angle difference would help to strengthen the agitation in the system. However, further investigation indicated that the difference in tuyere angle between two rows of tuyeres should be limited within a certain range to balance the requirements of higher agitation efficiency and longer lining refractory lifespan.

This article introduces a novel control strategy for the uncertain eye-to-hand system, which is considered to work with unknown model of constraint surface and uncalibrated camera model. Besides, the uncertain dynamics and kinematics are also included in the system. In order to be closer to the real robot system, we also consider it with dead-zone inputs situation. So the parameter intervals and slopes of the dead-zone model is also unknown. Hence, a novel adaptive image-based visual servoing (IBVS) and force control approach is put forward. The control method of unknown force and uncalibrated camera model is achieved by adaptive control. The solution of unknown dead-zone inputs is completed by designing a inverse smooth model of dead-zone inputs to offset the nonlinear affect due to the actuator constraint, and the whole system is proved that the force tracking control and image position converge to zero asymptotically. Finally, the MATLAB simulation is set up and the experiment shows the validity of the proposed scheme.

This article proposes and implements a multi-topological low-frequency-switching (LFS) high-frequency-resonating (HFR) wireless power transfer (WPT) system, which can significantly improve the system efficiency and fluctuations for specific HFR-WPT applications at equal power level. To adjust the HFR wireless power, high-frequency-switching phase-shift control (PSC) will increase the switching loss and operating temperature, thus inevitably degrading the system efficiency and stability. With the system optimization for suppressing current fluctuations, an LFS-PSC technology is deeply investigated to control wireless power while reducing the switching and conduction losses. Also, it can effectively mitigate the adverse impacts of dead zones on the power and efficiency losses. The system efficiencies using two exemplified WPT topologies can reach 89.53% and 91.62%, while they can be improved by 2.75% and 2.13% during power control. The theoretical analysis, simulation, and experimentation are given to verify the feasibility of the proposed systems using LFS-PSC.

In this paper, a CMOS based precharged phase frequency detector (PPFD) with improved output characteristic for phase locked loop (PLL) has been proposed and analyzed. The proposed PFD minimizes the reset time to improve the output characteristics and works upto the frequency of 1.25 MHz–3.8 GHz. In addition, it has an advantage of precharged PFD which has low power consumption capability i.e., 285.77 $$\upmu$$ w. The design is based on standard 0.18 $$\upmu$$ m CMOS process technology with the supply voltage of 1.8 V and achieves phase noise of $$-135.45$$ dBc/Hz at 1 MHz offset. Further, the proposed design has minimized the Blind zone to 63 ps and has completely eliminated the dead zone in the phase characteristics. This is required for low noise phase locked loop (PLL) application.

This paper describes experimental research on the wall normal stress in a laboratory-scale coal silo. The stresses were measured during discharge by pressure sensors arranged in the wall of the silo. The results show that the wall normal stresses at the upper part of hopper remain fairly constant for about three-fourths of the discharge, and then oscillate violently. The dead zone and the saturation effect of pressure in silo contribute to the smoothness and steadiness of those stresses in the stable stage of discharge. A tentative procedure is proposed to predict the funnel flow pattern of which the lower merge point has some distance from the edge of the outlet. Furthermore, a large fluctuation traveling upward from the outlet was detected during the initial discharge period. The movement of the lower merge point, which changes the flow pattern and stress state zone, is reasonably responsible for the large fluctuation.

The introduction and development of computerized digital systems in modern power engineering has led in Russia to a full modernization of domestically produced nuclear power plant measurement systems. In particular, digital methods for correcting the readings of hydrostatic level sensors have been widely put in use since 2013. The experience gained from putting them in use was generalized in the reference and organizational and methodological literature in 2017. However, the subsequent results of preoperational adjustments carried out at newly designed nuclear power units and at those under construction have shown that some issues still remain unresolved in this application field. In particular, there is a need is to develop digital methods for correcting the readings produced by channels measuring the level of liquid media in pressurized process tanks if there occurs a sensor dead zone. The complexity of this problem is stemming from the fact that it is not possible to take the sensor dead zone into account by introducing a constant correction to the measurement channel readings in view of the technological process peculiarities. Thus, during the operation of nuclear power units, the water density in pressurized process tanks and vessels decreases from 980 to 590 kg/m3, and the vapor density increases from 0 to 100 kg/m3. Such changes give rise to complex thermal and physical interphase processes that occur under the conditions of large mass transfers of the vapor--water mixture. As a result, the sensor's dead zone boundary undergoes an essential change in the tank longitudinal section depending on the current values of the working fluid thermal and physical characteristics. To solve this problem, digital methods for online correction of measured level readings are proposed that take into account changes in the two-phase working medium (vapor--water) in the course of a continuous technological process. Nowadays, the introduction of digital methods for correcting the hydrostatic level sensor readings is especially relevant in connection with the development of industry programs aimed at increasing the capacity of newly designed and operating nuclear power units, which pose more demanding requirements to the accuracy of thermal and physical measurements and operational safety as a whole.

This paper addresses the finite-time tracking control problem for a class of nonaffine nonlinear systems with unknown dead zones using an adaptive fuzzy control scheme. The unknown nonlinear functions of the system are approximated by the fuzzy logic systems and a finite-time stability theorem is used to construct the control signal. The novelty of the proposed control method is that the tracking system can reach the stable equilibrium within a finite period of time without the knowledge of the boundaries of the dead zone parameters. The simulation results show that the system is semi-global practical finite-time stable and the tracking deviation converges to a small neighborhood of zero in a finite period of time.

Background: Diagnostic ultrasound or sonography is an image which can provide valuable information for diagnosing and treating a variety of diseases and conditions. This experiment was done to check the performance and evaluate the ultrasonic imaging system. There were three tests performed in this experiment: dead zone (transducer ring-down), vertical measurement calibration, and horizontal measurement calibration. Methods: The evaluation was made by performed all the tests with different depth on two different multipurpose phantom model #539. The tests were also performed by two different probes which were curved and flat (linear probe). The images were taken, and the measurements were made by electronic calipers on the ultrasound machine system. Observations and evaluations were done via all images and measurements taken. Results: The images formed by two various probes were different. The penetration settings were different since the depths were different. The depth influenced the penetrations to the formed image. From the comparison of all results and measurements recorded were all under the accepted value of the standard that was given by the manufacture of the phantom. Conclusion: Therefore, it can be concluded that the measurements were all not exceeding 2% of the standard value given based on the result that we get.

This study presents the optimization of signal coverage area in third generation WCDMA technology of mobile communication networks, aim at improving signal coverage area or overcoming the presence dead zone in mobile communication network. Various parameters that affect Signal coverage area in mobile communication network were determined. Optimization mathematical model based on Lagrange mathematical method was developed in line with the necessary parameters and characteristics. The developed mathematical model was simulated using MATLAB and Wolfram Mathematical Software using data obtain from mobile communication Network ‘A’ at Asaba, Delta State. The obtained data were number of duplex channels, frequency, load capacity of the base station, interference, distance power received, power transmitted etc. The result obtain are the critical points with fade-off of the radio signal. The coverage area indicates a non-linear function, therefore to minimize threshold parameter such as interference; pathloss and power received values will increase as the coverage area of the base station increases.

Background & Introduction: With the advent of technology, though the literature highlights many designs of Phase Frequency Detector (PFD), there remains some challenges like area overhead, switching noise near frequency lock point and fast, accurate response to mitigate dead zone and output errors. Methods: In this article, we have unearthed a low power, high speed and dead zone free PFD, which eliminates the switching noise near that lock-in node. This simple design uses lesser number of transistors to obtain smaller estimated layout area of 0.748mm2 and low power of 496.12μW, when operated at 10 GHz frequency at a power supply of 1.8V in 90nm CMOS technology. Results: The simulation reads a phase noise and output noise of -113.142dBc/Hz and -180.712dB at 1MHz offset. The circuit not only runs at a frequency as high as 40GHz, but also compatible to be operated at a power supply of as small as 0.9V. Conclusion: Process Variation analysis performed proves the robustness of the proposed circuit at all process corners. Also, the design gets validated at lower process nodes like 28nm UMC.

This paper proposes a global path planning for lunar rovers in polar regions under static and dynamic constraints. Prior to lunar mission launch, a specific mission path must be set for a lunar rover. The mission path is generated under uncertain information. Only lunar digital elevation model (DEM) and secondary parameters derived from DEM are available. The parameters can be divided into two categories: static parameters and dynamic parameters. Parameters such as DEM, slope, and roughness can be categorized into static parameters. Illumination and thermal inertia can be categorized into dynamic constraints. This paper introduces such parameters as constraints for path planning, by either giving weight to each parameters or suggesting a threshold for a dead zone. A* path planning method is used to implement such parameters as constraints. Simulations of path planning are shown.

There are several configurations of fluidized beds commonly used in wastewater treatment units. Often their hydrodynamics is challenging to be evaluated experimentally, or too complex to be predicted accurately with empirical correlations only. In the present study, the computational fluid dynamics technique was applied to evaluate the hydrodynamic behavior of a liquid–solid fluidized bed in tapered bioreactors. The simulations were run with OpenFOAM, and they were based on a 3D, transient, Eulerian–Eulerian two-phase approach coupled with a turbulence model. Different tapered bioreactor angles were considered in the study, and the results showed a decrease in flow velocity along with the height of the device. Moreover, the distribution of the bioparticles within the fluidized bed was not found to be uniform, and it changed with the angle. It was also observed that bioparticle collisions caused large velocity fluctuations. Even though the bioreactor presented a square cross section, results also proved that the presence of the dead zone was negligible.

In this article, a novel design is presented, for an Integer- N charge pump phase locked loop (PLL). The design is with a resetless phase frequency detector, and with the differential design of charge pump. The voltage-controlled oscillator is of current starved type. The proposed PLL is not having any blind zone and is having near-zero dead zone. When compared to the conventional design, the current mismatch in the charge pump is reduced by 3.21%, and the lock time of the PLL is reduced by 79%. The PLL is intended for 2.4 GHz application, and the obtained lock time is 1.7 μs. The implementation is done with the three-stage ring oscillator, with divider of modulus as 24, in 180 nm TSMC technology. At 1.8 V supply voltage, the circuit consumes 9.72 mW of power.

The sensing coverage and accuracy of vehicles are vital for autonomous driving. However, the current sensing capability of a single autonomous vehicle is quite limited in the complicated road traffic environment, which leads to many sensing dead zones or frequent misdetection. In this paper, we propose to develop a Vehicular Fog Computing (VFC) architecture to implement cooperative sensing among multiple adjacent vehicles driving in the form of a platoon. Based on our VFC architecture greedy and Support Vector Machine (SVM) algorithms are adopted respectively to enhance the sensing coverage and accuracy in the platoon. Furthermore, the distributed deep learning is processed for trajectory prediction by applying the Light Gated Recurrent Unit (Li-GRU) neural network algorithm. Simulation results based on real-world traffic datasets indicate the sensing coverage and accuracy by the proposed algorithms can be significantly improved with low computational complexity.

This work investigates the adaptive neural tracking control problem for a class of uncertain switched nonlinear non-lower triangular systems with disturbances and dead-zone input. First, radial basis function (RBF) neural networks (NNs) serve as a flexible tool to approximate the unknown nonlinear functions. Then during the controller design, the dynamic surface control (DSC) method is used to avoid the issue of “explosion of complexity”, and only one adaptive law is adopted to reduce the computational burden. What’s more, a few classical mathematical approaches are used to handle the design difficulties caused by dead-zone input, and the proposed controller guarantees the closed-loop system signals are semi-globally uniform ultimate boundedness (SGUUB). Finally, a simulation example is given to illustrate the availability of the proposed control scheme.

The compatibility of computer-aided design (CAD) with computational fluid dynamics (CFD) softwares was used to establish a digital and lean development method for 3D-printed reactors which allows for shorter development cycles and targeted process setup. CAD modeling, as the starting point of an additive manufacturing process, creates 3D-designs, which can be directly evaluated by CFD simulation. Thus, challenging assumptions or issues regarding the performance of a tubular reactor can be visualized and redefined to create iteratively new strategies and solutions in a cost- and time-effective way. Our approach enables to build and deliver reactor designs incrementally and faster as it can be performed digitally and tailored to specific requirements. The developed reactor design subsequently can be fabricated directly by 3D printing techniques. The method is based on an established 3D-printed tubular bended reactor for emulsion polymerizations, without being limited to a specific case and enabled the lean fabrication of a tubular reactor being developed to proactively use Dean vortices by reducing dead zones in a more compact design. Optimized flow patterns were further obtained by the tailor-made implementation of static mixing elements at targeted positions of the reactor design.

The general information on the existing automatic devices for the elimination of the asynchronous operation (AEAO) and their application on overhead power transmission lines (OHL) is given, as well as deficiencies in their operation in terms of blocking by the minimum voltage are noted. The presence of "dead zones" of the AEAO device actuation according to the "angular" principle, that are detected during tests on the given settings, is shown. An experience exchange gained during the commissioning of AEAO devices on 110 kV overhead power transmission lines in the electrical network of the distribution grid complex of the branch of PJSC Rosseti Kuban was carried out. The methodology for calculation of the "dead zones" of the AEAO device actuation and taking them into account in the design, as well as in the formation of the task for the settings of the AEAO device is recommended.

Centrifugal blood pumps are usually designed with secondary flow paths to avoid flow dead zones and reduce the risk of thrombosis. Due to the secondary flow path, the intensity of secondary flows and turbulence in centrifugal blood pumps is generally very high. Conventional design theory is no longer applicable to centrifugal blood pumps with a secondary flow path. Empirical relationships between design variables and performance metrics generally do not exist for this type of blood pump. To date, little scientific study has been published concerning optimization and experimental validation of centrifugal blood pumps with secondary flow paths. Moreover, current hemolysis models are inadequate in an accurate prediction of hemolysis in turbulence. The purpose of this study is to optimize the hydraulic and hemolytic performance of an inhouse centrifugal maglev blood pump with a secondary flow path through variation of major design variables, with a focus on bringing down intensity of turbulence and secondary flows. Starting from a baseline design, through changing design variables such as blade angles, blade thickness, and position of splitter blades. Turbulent intensities have been greatly reduced, the hydraulic and hemolytic performance of the pump model was considerably improved. Computational fluid dynamics (CFD) combined with hemolysis models were mainly used for the evaluation of pump performance. A hydraulic test was conducted to validate the CFD regarding the hydraulic performance. Collectively, these results shed light on the impact of major design variables on the performance of modern centrifugal blood pumps with a secondary flow path.

A disturbance observer-based control scheme is proposed in this paper to deal with the attitude stabilization problems of spacecraft subjected to external disturbances, parameter uncertainties, and input nonlinearities. Particularly, the proposed approach addresses the dead-zone issue, a non-smooth nonlinearity affiliated with control input that significantly increases controller design difficulties. A novel nonlinear disturbance observer (NDO) is developed, which relaxes the strong assumption in conventional NDO design that disturbances should be constants or varying with slow rates. After that, a special integral sliding mode controller (ISMC) is combined with the NDO to achieve asymptotic convergence of system states. Simulations are performed in the presence of time-varying disturbances, parameter uncertainties, and dead-zone nonlinearity to justify the effectiveness of the proposed control scheme.

This paper investigates adaptive attitude control for quadrotor unmanned aerial vehicle (UAV) with dead zone and external disturbance. A attitude controller is designed based on backstepping, and adaptive law is designed to compensate the influence of input dead zone and external disturbance. The designed controller guarantees that attitude angle of quadrotor UAV can trace the desired attitude angle. Finally, simulation results have demonstrated the effectiveness of the designed scheme.

Many applications, such as multi-standard wireless and event-driven IoT devices, demand high-resolution ADCs with scalable sampling rate and power consumption. The conventional pipelined ADC can achieve high resolution, but its power does not scale well with the sampling rate due to the use of a closed-loop static OTA for residue amplification. While the OTA can be turned off to save power, it requires considerable time for the bias circuit and CMFB loop to settle when waking up, leading to wasted power and reduced peak operation frequency. Using an open-loop dynamic amplifier can make power scale linearly with frequency, but its gain varies with PVT and often requires background calibration, which converges slowly and is incompatible with eventdriven applications. The ring-amp is a promising solution as it features closed-loop operation, easy duty-cycling, and decaying power over time [1] –[4]. However, its stability depends on the dead zone size, which typically requires trimming across PVT variations. Besides, the $1 ^{st}$ stage has a constant operating point during amplification, which consumes considerable energy. A recent work proposed a 2-stage floating inverter amplifier (FIA) that is fully dynamic and works in closed-loop [5]. It guarantees stability and does not need dead zone control. Moreover, the power consumptions of all stages decay over time naturally. Nevertheless, its low open-loop gain of 33dB is inadequate for a high-resolution pipelined ADC, and its fast-quenching $2 ^{nd}$ stage reduces the amplifier speed, limiting the usage in high-speed designs.

Fixed-frequency Air Conditioning Load(FACL) is the most widely used demand response resource on the user side, and has the characteristics of simple scheduling. In this paper, the operating characteristics of FACL are studied starting from a single device, and the aggregation model of FACL is established. The ratio between the difference value of indoor temperature relative to the dead zone boundary and the dead zone operating temperature of a single FACL is defined as Normalized Temperature Adjustable Capacity (NTAC). Based on NTAC, a temperature control strategy of FACL participating in demand response is proposed in this paper. Simulation results show that this strategy can achieve power extraction without generating rebound load, and has a good engineering application prospect.

In this investigation, we describe a spectrally resolved polarizing interferometer to modify the typical spectrally resolved interferometer based on the Fourier method, which has a dead zone caused by the minimum measurable range. By use of a polarization pixelated CMOS camera, which enables us to obtain spatially phase-shifted spectral interferograms, the spectral phase can be extracted with a single image, and the proposed interferometer can obtain a line profile of a specimen at once. By the nature of phase-shifting technique, moreover, the directions of the measured distances can be identified, and the measuring range is extended to twice that of the typical spectrally resolved interferometer. In the experimental results, the measuring range was 104 µm, and the capability to obtain a line profile of a specimen with a single image was confirmed. For 3D surface profiling, lateral scanning was adopted, and the measurement results were compared with the result of the Fourier method.

With the penetration of distributed generation (DG) increased rapidly, and the DC load equipment used widely. The AC/DC Hybrid Microgrid shows great superiority, but we still face some critical problems. For example, the transient stability of power and frequency should be better to meet the increasing demand for high quality power supply. The interlinking converter (ILC) is the bond which connects microgrids. In order to reduce the transient disturbance of the power and frequency when the power communicate between the AC side and the DC side, the improved adaptive damping coefficient based on virtual synchronous generation (VSG) control strategy was proposed in this research. And the reference power signal comes from the Bilateral droop control with dead zone. In order to verify the effectiveness of the strategy, the simulation model was built in Simulink. The simulation results show that the control strategy has better control performance of the power and frequency.

Membrane BioReactor (MBR) is a commonly used technology in wastewater treatment; however, fouling is the main drawback of MBR. Grundfos proposes a system that splits the technology into two parts: the biological tank and the membrane system. The latter rotates to decrease and mitigate the fouling. This paper evaluates two membrane configurations, a central and eccentric axis. The shear stress profile in a single rotating membrane was obtained through CFD modelling with different operating conditions that show that an increasing TSS or angular velocity causes an increment in the shear stress over the membrane surface. Additionally, based on the CFD results and empirical correlations, a factor α used to determine the shear stress for non-Newtonian fluids was calculated in order to predict the behavior for central and eccentric placement configuration MBRs. The velocity profile in a wagon of 36 membranes was obtained from CFD simulations, where it was evident that eccentric placement is the best option since it reduces the dead zones and increases the shear stress, which helps reduce fouling.

In response to the requirement of a large amount of historical data storage and the difficulty of data analysis and visualization in the industrial equipment data acquisition system, a data compression method based on operation condition identification is proposed in this paper. The method firstly sets the dead zone limit value for each dimensional time series according to the change of multi-dimensional time series data collected from industrial equipment; then, on the grounds of whether each piece of data meets the dead zone limit, collecting equipment operation condition information and marking operation condition labels; finally, based on the operation condition label, the data is compressed into a data matrix composed of time and operation condition information. Our storage method has good universality and realizes efficient data storage by reducing the dimension of historical data.

In this paper, based on adaptive non-backstepping design algorithm, we proposed a novel variable universe fuzzy control (VUFC) algorithm for a class of MIMO nonlinear systems with unknown dead-zone inputs in pure-feedback form. First, by introducing some new states variables and coordinate transforms, the system is converted form the state-feedback control of pure-feedback form into the output-feedback control of normal form. Secondly, different from traditional backstepping scheme,we introduce contraction–expansion factors, combine non-backstepping control technique and VUFC scheme together to construct the controllers and observers. VUFC approach is mainly based on changing the contraction–expansion factor to change the universe of the variables (which can change the interpolation node encryption). It is shown that the proposed control approach is considerably simpler and better than the backstepping-based ones and it can improve the accuracy of the system, alleviate tracking error, strong robustness. At last, according to stable positive real (SPR)-Lyapunov stability analysis, it can guarantee that all the signals in the closed-loop system are bounded and the output can tack the reference signal to a small neighborhood of the origin. Simulations results are illustrated that the effectiveness of the proposed VUFC approach.

A novel method, to the best of our knowledge, of fiber transfer delay (FTD) measurement based on phase quantization and delay synthesis is proposed and demonstrated. By detecting the differential phase shifts of a set of frequency-multiplied RF signals transmission through the fiber link with and without the FTD under the test, the 2 π phase ambiguity problem can be solved. To avoid the phase quantization error near the digital quantization boundary, a self-check and error-correction method is proposed so as to greatly improve the reliability of measurement. In the experiment, the measurement repeatability around 0.018 ps within a period of 80 s is achieved for a back-to-back fiber link, and a test resolution of 0.03 ps is proved with a motorized tunable delay line. The system is available for measurement of a large FTD range up to 100 µs with no dead zone.

The optimum shapes of vertical double agitators installed in a rectangular tank of sewage disposal plant are numerically investigated to improve the stirring performance. The domestic sewage disposal plant generally consists of three tanks; a bioreactor tank, a phosphorus release tank, and a flow adjustment tank. In each rectangular tank, an agitator is installed. The major role of agitator is blending the sewage and decreasing the dead zone where the sewage sludge is accumulated. The sludge accumulated in the dead zone makes a water rotting. Therefore, the optimum shapes of vertical double agitator are newly designed to reduce the dead zone and to increase the stirring performance. Also, the operating conditions of vertical double agitators are studied to avoid the creation of dead zone in a rectangular tank.

In the process of mode coupling measurement in FMF, the reflection from the front facet of the fiber generates a dead zone, which seriously affects the accuracy of the measurement. This paper analyzed mode coupling over FMF based on Rayleigh backscattering and built an experimental system using two photonic lanterns as the mode converter and demultiplexer respectively. And then we successfully measured the mode coupling distribution along a 4-km six-mode fiber. The values of the mode coupling coefficients obtained with the experimental system agreed well with those obtained with the conventional transmission method, and the deviations were less than 0.66 dB/km while the deviations were more than 1.31 dB/km using other experimental system which cannot eliminate the Fresnel reflection when a 300 ns optical pulse was coupled into the LP01 mode. The experimental system based on two photonic lanterns can eliminate the Fresnel reflection and the associated dead zone from the front facet of the fiber.

In this work, we studied the flow characteristics of particulates in a novel moving granular bed by using experiments and numerical simulations. The new moving granular bed was equipped with one adjustable baffle and two slopes to adjust filter thickness and increase the gas-particle contacting surface. Doing so overcomes the poor adaptability and low collection rate of fine dust during the filtration, and improved the filtering performance of filter devices. In the experiment, the movement of particulates in a moving bed was recorded using a camera, and the effects of the device structure and the filter moving speed on the flow of filter particles were examined. Combined with Discrete Element Method (DEM) to simulate the velocity variation of particles in the granular bed, the mechanism of particulate flow was analyzed. The inclined surface was found to affect the flow of filter particles, and a small angle of inclination was not conducive to the particle flow. Therefore, a layer of dead particles was easily formed. The dead zone particle layers on the left slope could protect the insulation layer and the heat insulation layer outside the particle bed. Increasing the moving speed of the filter increased the velocity difference between the particles in the wall surface and the middle part. The fluidity of particles also increased to make the particle layer of dead area become thinner. The trajectory of a single particle was greatly affected by the overall moving speed, and the single particle tended to move toward the faster direction in the same plane with the increase of the filter moving speed.

Requirements are determined for the spontaneous Raman lidar transceiver system, designed for solving problems dealing with studying the atmospheric boundary layer and predicting dangerous smog situations. The optical scheme of a lidar transceiver system with a narrow field of view and minimal dead zone is synthesized. The results of computer simulation of the lidar overlap functions obtained by the ray tracing method for few optical schemes of the receiving optical system are presented. It is shown that when a multielement transceiver based on a combination of four receiving apertures of different diameters is used, a lidar sensing range can be from 5 to 3000 m for the dynamic range of the lidar response of no more than 10.

The structural characteristics of a spiral symmetry stream anaerobic bioreactor (SSSABR) contribute to its super-high-rate performance. This study investigated the structural characteristics of SSSABR, including distribution zone, spiral reaction zone, and three-phase separation zone, by computational fluid dynamics (CFD). In distribution zone, uniformity and hydraulic head loss increased with increasing number of orifices, and five-orifice is deemed optimal for distributor. In spiral reaction zone, a 45° cutting angle produced a tangential velocity strong enough to spin the granular sludge and maintain a moderate mixing intensity. A 30° installation angle produced a wide range of spiral flows. The 120° symmetrical arrangement of plates formed a strong–weak periodic spiral flow that strengthened material exchange. In separation zone, a value of 0.625 for the frustum characteristic parameter i (i = r1/r2, where r1 presented the bottom frustum radius of reverse cone, and r2 presented radius of spiral reaction zone of SSSABR) provided moderate recirculation. The relative error of dead zone rate between CFD and tracer experiment was 4.66%.

Due to the benefit of multiple parallel channels within single cladding and easy implementation of multi-input multioutput technique, we present the spatial division multiplexing (SDM)-based reflective intensity-modulated fiber optics displacement sensor (RIMFODS). Under the condition of single-input single-output, we experimentally compare the transfer function of RIMFODS by using a pair of standard single-mode fibers (SSMFs), single seven-core-single-mode fiber, and single seven-core-few-mode fiber. In comparison with the conventional SSMF-based RIMFODS, the use of seven-core-few-mode fiber can reduce the dead zone of measurement range from 200 to 100 μm. Meanwhile, the system sensitivity can be enhanced from 0.14 to 12.2 nW/μm. In particular, with the help of two-input-five-output technique, the dead zone can be further reduced to 70 μ m, with sensitivity reaching as high as 53.87 nW/μm. Finally, we theoretically investigate the effect of both the core size and the core spacing of multicore fiber on the transfer function of RIMFODS. Such an SDM-based RIMFODS with compact footprint has lots of potential to be exploited.

This study aimed to use a Computational Fluid Dynamics (CFD) simulation of a tray dryer to investigate the possible causes of non-uniformity in the absolute final product humidity after the drying process in an empirically constructed tray dryer. In the experimental part, turmeric, which is the rhizome of a perennial herbaceous plant with interesting properties for the cosmetic and food industries, was dried. Pieces of turmeric with identical dimensions were placed in different zones of the dryer and their initial and final humidity values were empirically measured. In the simulations, the momentum and energy equations were solved with ANSYS software (Student v.17.2). The K-epsilon model was used to model the turbulence and the boundary and process conditions were identical to those used in the experiment. Although the steady-state CFD simulations show a homogenous local temperature distribution in the dryer, the local turbulence intensity profiles display dead zones with low turbulence values. Furthermore, these dead zones are consistent with areas where the product exhibits higher humidity. Low local turbulence values can negatively affect the local mass transfer coefficient, which may explain the experimental results of this study.

We have previously demonstrated a photonic time-stretched coherent radar (PTS-CR) with central-frequency programmable and bandwidth-tailorable agility. The sampling bandwidth in the reception was essentially compressed by the photonic time-stretched process. However, in the PTS-CR, the reception aperture suffering dead zone was hardly tuned by the fiber delay line and the measurement range was restricted by the pulse repetition rate (PRR) of the mode-locked laser. Here, we report a novel scheme to overcome the restrictions. The reception aperture can be simply tuned by adjusting the center wavelength of an optical filter and the PRR is reduced for enlargement of the measurement range by use of a photonic switch in the transmitter. In the experiment, a tenfold enlargement of measurement range is demonstrated to identify two neighboring targets separated by ~4 cm.

In this study, the effects of length-width ratio and diversion trench of the spacer on the fluid flow behavior in an electrodialyzer have been investigated through CFD simulation method. The relevant information, including the pressure drop, velocity vector distribution and shear stress distribution, demonstrates the importance of optimized design of the spacer in an electrodialysis process. The results show width of the diversion trench has a great effect on the fluid flow compared with length. Increase of the diversion trench width could strength the fluid flow, but also increase the pressure drop. Secondly, the dead zone of the fluid flow decreases with increase of length-width ratio of the spacer, but the pressure drop increases with the increase of length-width ratio of the spacer. So the appropriate length-width ratio of the space should be moderate.

Study of dynamic performance of variable stiffness actuators has become more important for high safety in human-robot interaction. In this paper, based on the human knee joint, a variable stiffness actuator for the knee joint is proposed and its feasibility is experimentally verified. Then by considering connection compliance between motor and internal load inside actuator, two-inertia-system model is developed, and the accuracy of this model is experimentally verified. Finally, effects of friction and gap characteristics on the dynamic performance of this actuator are analyzed. Results show that both gap and friction characteristics have significant effects on the dynamic performance of variable stiffness actuator with high precision and micro-motion, and they both cause significant dead zones when forward and reverse rotations of motor are transformed; During adjustment of stiffness, variable stiffness actuator is caused to vibrate by gap, and motor is required to provide more energy to counteract effects of friction. So the control of variable stiffness actuator still needs to be studied more thoroughly to meet requirements of vibration suppression and high accuracy.

Defect detection during pulse-echo ultrasonic testing (UT) is challenging when defects are located in a dead zone where the echoes from the defects are overshadowed by disturbances from the initial ringing signal of the UT transducer. The time-gate method is one of the most widely used approaches in UT to filter out such unwanted components, but defects in the dead zone are virtually impossible to detect using conventional methods. This paper proposes an autoencoder-based end-to-end ultrasonic testing method to detect defects within the dead zone of a transducer. The autoencoder is designed to predict the normal behavior of ultrasonic signals including disturbances, thus enabling the identification of even subtle deviations made by defects. To advance the performance of the autoencoder further with a limited amount of training data, a two-step training procedure is presented, involving training using pure normal signals measured from a defect-free specimen and re-training using pseudo-normal samples identified by the autoencoder with a smart thresholding strategy. This two-step procedure enables us to develop an adaptive autoencoder model that can be effectively employed to process the newly measured ultrasonic signals. For a demonstration of the proposed method, UT-based B-scan inspections of aluminum blocks with near-surface defects are conducted. The results suggest that the proposed method outperforms the conventional gate-based inspection approach with regard to its ability to identify the sizes and locations of near-surface defects.

An on-line compensation for the dead time strategy without the knowledge of the current direction is proposed for PMSM drive based on a current observer. The modifications of the motor reference voltages are achieved by an uncomplicated current observer working in conjunction with the feedforward dead time voltage estimator. Therefore, the distortions on phase currents and torque due to dead time are greatly reduced. The proposed method does not require look-up table and coordinate transformations. It also does not need phase current polarity information or calculation of dead time period. Since the proposed scheme requires no extra hardware and time consuming signal processing algorithms, it is appropriate to use in real-time implementation of AC drives. The proposed scheme has been validated in simulation and implemented using TMS320F28335 DSP. Simulation and practical results validate the effectiveness and the feasibility of the proposed scheme.

This study presents the behavior of residual chlorine using computer modeling for a small water supply system located in La Sirena, Cali, Colombia. The study included field work to calibrate and validate the model together with lab determinations. Results show that the kinetics of first and second order together with the kinetics of mixed order can adequately describe the behavior of residual chlorine in this type of network. The research showed the variables that influence the behavior of residual chlorine in the network are: the quality of the input water, chlorine dosing, the effect of storage that increases the water age, and the presence of dead zones in the tanks. The study revealed that 95% of the reaction occurs in the storage tanks due to the small variation in the water level and the negligible reactions at the pipe walls. This study proved that the residual chlorine modeling in this small network in particular is a valuable tool for monitoring the water quality in the distribution network, which is useful to comply with water quality guidelines.

A three-dimensional computational fluid dynamics model with consideration of both heat transfer and material flow has been developed. The heat generation model from a previous study was adopted. The temperature predictions have a good agreement with experimental measurements, showing that material flow during the friction extrusion process has limited influence on heat transfer. Small solid particles were used as tracked markers in the fluid in the modeling to capture the material flow pattern. The path lines of the particles compare well with experimental observations. The material in the central region is pushed spirally upwards toward the extrusion hole to form the extrusion wire, the near material moves spirally to fill the central region, and there is a dead zone in the process chamber where the material always stays in the chamber and will not be extruded out.