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To achieve fast, accurate control of the position angle of the rotor of permanent magnet synchronous motor (PMSM), traditional auto disturbance rejection control often has many adjustable parameters and complex tuning problems. Sliding mode control technology is introduced into the extended state observer (ESO) part of the auto disturbance rejection controller, and a new sliding mode approach law is designed based on several typical sliding mode approaches, which simplifies parameter tuning while retaining the original anti-interference performance of auto disturbance. In addition, the nonlinear state error feedback control law in active disturbance rejection control is enhanced to improve the component order PID control law, which can improve the response speed and robustness of the system, and prove the stability of the controller. Finally, the simulation of the PMSM rotor position control system based on the sliding mode ESO is carried out, and the results verify the validity of the method. [ABSTRACT FROM AUTHOR]

This paper proposes a dynamic characteristic improvement of an integrated on-board charger (OBC) using a model predictive control (MPC) method. The integrated OBC performs both battery charging and starter generator (SG) driving for engine starting in plug-in hybrid electric vehicles (PHEVs). If it performs battery charging, battery-side voltage and battery-side current are control objects which are usually controlled by using a proportional-integral (PI) controller. However, it has the disadvantage of undesirable dynamic characteristics, and gain tuning of the PI controller is necessary to properly control the voltage and current. Therefore, this paper proposes the MPC method for the dynamic characteristic improvement of integrated OBC. It can achieve not only dynamic characteristic improvement, but also robustness from the abrupt change of load impedance. By using the proposed MPC method for integrated OBC, the settling time to control the output voltage is decreased by 50% in the transient state compared to that by using the PI controller. The effectiveness of the proposed MPC method is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

One of the main problems in the operation of cranes is the oscillation of the load on a flexible suspension. One of the ways to eliminate load oscillations on a flexible suspension is to use a proportional-integral-differential controller that generates a control signal for the crane movement. However, for it to function properly, it must be properly tuned. Standard approaches to tuning a PID controller, which is common in the practice of engineering calculations, do not allow solving this problem, and that is why it can be considered as a scientific and applied one. The research aims to develop an algorithm for tuning a proportional-integral-differential controller. For this purpose, a research issue was defined, which includes a mathematical model of the dynamic system, constraints on the overload capacity of the crane drive and the control function, conditions for achieving the steady-state speed of the crane and eliminating pendulum oscillations of the load on a flexible suspension. Using the modified particle swarm method, ME-D-PSO, the coefficients of the proportional-integral-differential controller were determined for a wide range of values of the load mass and the length of the flexible suspension. Based on the obtained values of the coefficients, an algorithm is presented that allows calculating the values of the coefficients for any values of the load mass and the length of the suspension. The dynamics of the movement of the crane-load system are analyzed for the smallest and largest selected parameters and for the case obtained by applying the developed algorithm. Practical application of the developed algorithm will allow obtaining optimal values of the proportional-integral-differential controller, which in turn eliminates oscillations of the load on a flexible suspension during crane operation, which in turn increases the safety of crane operation, structural durability, and increases the crane's capacity. [ABSTRACT FROM AUTHOR]

This paper presents characterization and compensation of the thermal bias drift of a MEMS accelerometer whose effective stiffness is electrostatically tuned to a low value with the help of the single-sided parallel plates (SSPPs) capacitors. A temperature drift model for the proposed accelerometer is built and the temperature effect on the mechanical stiffness and the circuit gains is characterized. The characterization reveals that the variations of the feedforward coefficient including the mechanical stiffness and the readout gain due to the temperature change play a significant role in the bias drift of output of the proposed closed-loop accelerometer. On the other hand, the variations of both feedback gain and tuning gain as a function of temperature are one-order-of-magnitude less than that of the feedforward coefficient. To calibrate the feedforward coefficient, an excitation signal as a form of AC reference displacement is introduced to drive the proof mass and the readout response is demodulated to calibrate the variance of the feedforward coefficient correspondingly. An open-loop compensation scheme for the temperature-induced bias drift using the variance of the calibrated response is proposed accordingly. Alternatively, the calibrated response can be controlled to a preset value by a new proportion integral derivative (PID) controller by the adjustment of the SSPP tuning voltage. The output of the PID controller is used for the calibration of the introduced bias from the electrostatic tuning force. Therefore, a closed-loop compensation of the thermal bias drift is achieved by remaining the feedforward coefficient while eliminating the calibrated bias. Experiments under a temperature cooling process and different tuning voltages are carried out to verify two proposed compensation schemes. The temperature drift coefficients (TDCs) of both compensated outputs exhibit at least one-order-of-magnitude reduction in response to the temperature change. When the effective stiffness of the accelerometer is tuned to about 4.19 N mâˆ'1, the TDC of the compensated output using the proposed open-loop or closed-loop compensation schemes is reduced to about 0.1136 or 0.0391 mg °Câˆ'1, respectively and meanwhile, the Allan bias instability is slightly increased to 48.63 or 56.14 ÎĽ g, respectively. [ABSTRACT FROM AUTHOR]

In this study, an Adaptive Cruise Control system is designed by using conventional Proportional Integral Controller (PID) and Model Predictive Controller (MPC). In the design, vehicle, acceleration, and deceleration models are constructed in a way to simulate the reallife environment. The design and simulation were carried out through Matlab and Simulink. In order to investigate the effects of gains in the PID controller, several values for Kp, Ki, and Kd is tested. The simulation results illustrated that the gains Kp and Kd have negligible effects on the vehicle acceleration but the gain Ki has a substantial effect on the response of the ego car. The results of PID controller were compared with the results when the controller is replaced by MPC. It has been shown that the PID controller gives better results as compared to the MPC controller independent from Kp, Ki, and Kd values. Therefore, we can confidently state that the PID controller provides better responses in addition to its accessibility, simpler design, and cost advantages compared to the MPC controller. [ABSTRACT FROM AUTHOR]

This paper aims to present efficient efforts to optimize the proportional-integral-differential (PID) controller of clinker cooling in grate coolers, which have a fixed grate and at least two moving ones. The process model contains three transfer functions between the speed of the moving grate and the pressures of the static and moving grates. The developed software achieves the identification of the model parameters using industrial data and by implementing non-linear regression methods. The design of the PID controller follows a loop-shaping technique, imposing as a constraint the maximum sensitivity, Ms, of the open-loop transfer function and providing a set of PIDs that satisfy a range of Ms. A simulator determines the optimal PID sets among those calculated at the design step using the integral of absolute error (IAE) as a performance criterion. The combination of a robustness constraint with a performance criterion, Ms and IAE respectively, leads to an area of controllers with Ms belonging to the range of 1.2 to 1.35. The IAE is between 4.2% and 4.8%, depending on the set-point value. PID sets located near the middle of this area can be chosen and implemented in the cooler's routine operation. [ABSTRACT FROM AUTHOR]

Isoporous membranes consist of well‐defined micro and nanoscale pore architecture comprising uniform pore sizes with straight pore channels. In contrast to traditional random porous membranes with tortuous flow paths, isoporous membranes offer the opportunity to achieve a high degree of membrane customization and low pressure drop. Here, a physics‐based machine learning methodology that enables the predictive design of a single‐layer isoporous membrane in terms of the pressure drop is reported. In short, the methodology consists of a hybrid approach that includes experimental data on the variability of the pore architecture and the resulting pressure drop, training of a neural network with data from validated physics‐based simulations of laminar flow through the membrane, and Monte Carlo simulation (MCS) to stochastically account for the inherent variabilities of the pore architecture of fabricated isoporous membranes. Overall, the neural network and MCS predict the range of Δp for a given single‐layer membrane well. Experimental values fall within 90% of the minimum and maximum predicted Δp values. In addition, a sensitivity analysis with MCS is carried out to quantify how design and operating parameters affect the overall pressure drop. The methodology can be extended to membranes comprising multiple layers and to account for filtration efficiency. [ABSTRACT FROM AUTHOR]

• Ablation of collagen VI causes distinctive autophagic defects in different tissues and cell types. • In skeletal muscles, lack of collagen VI impairs autophagy induction, resulting in the detrimental accumulation of dysfunctional organelles both in mice and humans. • Autophagy dysregulation triggered by collagen VI deficiency relies on the persistent activation of the Akt/AMPK/mTORC1 signaling axis. • Targeting the autophagic process is a valuable prospective therapeutic strategy for collagen VI-related myopathies, currently under investigation in both the preclinical and clinical settings. • A number of collagen VI interactors in the ECM are involved in the fine tuning of the autophagy machinery, thus broadening the impact of collagen VI mesh on this cell process. Autophagy is a very versatile process through which the cell degrades damaged long-lived proteins, entire organelles, or pathogens, by engulfing them in characteristic double-membrane vesicles and conveying the cargo to lysosomes. It is a dynamic pathway tunable at multiple levels and responsive to nutrient and stress stimuli, also coming from the extracellular microenvironment and its remodeling. In the extracellular matrix, collagen type VI forms a distinctive set of beaded microfilaments that assemble into an intricate and multimodular meshwork of tightly linked proteins and surface receptors. When missing or defective, collagen VI triggers a series of pathological events in skeletal muscle and other tissues, with a remarkable impact on key cell processes, such as apoptosis and autophagy. In this review, we discuss the current knowledge about collagen VI regulation of autophagy in the different experimental models and human pathologies where it was studied, and provide some hints for future directions aimed at the fine dissection of this intriguing relationship, as well as its prospective translational impact for disease and therapy. [ABSTRACT FROM AUTHOR]

For on-shore and grout less design applications, the support structure for a rotating machine consists of a base-frame (base plate) normally known as skid. Most of the time these structures show up with high vibration on machine bearing cap due to structural resonance, unidentified cracks in joints of structural members. Detection and mitigation of such anomaly is time consuming job. The paper proposes a blueprint of design for active and passive resonance control at location without removal of base frame from foundation /main support and any structural modification which do not requires any hot work. [ABSTRACT FROM AUTHOR]

This paper proposes the development of a tuning methodology which can set the proper values of the Computer Numerical Control (CNC) parameters to achieve the required machining performance. For the conventional operators of machine tools, the CNC parameters were hard to be adjusted to optimal settings, which was a complicated and time-consuming task. To save time in finding optimal CNC parameters, the objective of this research was to develop a practical methodology to tune the CNC parameters effectively for easy implementation in the commercial CNC controller. Firstly, the effect of the CNC parameters in the CNC controller on the tool-path planning was analyzed via experiments. The machining performance was defined in the high-speed (HS) mode, the high-accuracy (HP) mode, and the high-surface-quality (HQ) mode, according to the dynamic errors of several specified paths. Due to the CNC parameters that have a particularly critical effect on the dynamic errors, the relationship between the CNC parameters and the dynamic errors was validated by the measured data. Finally, the tuning procedure defined the anticipated dynamic errors for the three machining modes with the actual machine. The CNC parameters will correspond with anticipated dynamics errors based on several specified paths. The experimental results showed that the HS mode was the fastest to complete the path, and the completion time of the HP and HQ modes were increased by 37% and 6%, respectively. The HP mode had the smallest dynamic errors than other modes, and the dynamic errors of the HS and HQ modes are increased by 66% and 16%. In the HQ mode, the motion oscillation was reduce significantly, and the tracking error of the HS and HP modes were increased by 85% and 28%. The advantage of the methodology is that it simplifies set-up steps of the CNC parameters, making it suitable for practical machine applications. [ABSTRACT FROM AUTHOR]

The output linewidth, temperature tuning range of BaGa4Se7 (BGSe) pumped at 1.06 μm and ZnGeP2 (ZGP) pumped at 2.1 µm are investigated. The output linewidth of the BGSe optical parametric oscillator (OPO) is 73 to 233 nm and 35 to 275 nm when the idler light is 2.93 to 7.65 μm (Type-I) and 3.01 to 8.9 μm (Type-II), respectively. The output linewidth of the ZGP OPO is 294 to 439 nm and 269 to 582 nm when the idler light is 3.11 to 3.36 μm (Type-I) and 5.69 to 7.75 μm (Type-II), respectively. The temperature tuning range of the BGSe OPO is 0.20 to 1.40 μm and of the ZGP OPO it is 0.10 to 0.29 μm when the temperature is from 300 to 500 K, respectively. [ABSTRACT FROM AUTHOR]

A flexible chassis (FC) is a type of electric vehicle driven by in-wheel motors that can be used in narrow conditions in agricultural facilities. The FC is composed primarily of four off-center steering mechanisms (OSMs) that can be controlled independently. Various FC operation modes can be achieved including cross motion (CM), in-place rotation (IR), diagonal motion (DM), and steering motion (SM). However, it is difficult to achieve satisfactory motion mode switching (MMS) results under traditional distribution control methodologies due to a lack of linkage relationships between the four OSMs. The goal of this study was to provide a coupling control method that can cope with this problem. First, dynamic MMS models were derived. Then, an MMS coupling error (CE) model was derived based on coupling control and Lyapunov stability theory. Second, a fuzzy proportional integral derivative (PID) controller with self-tuning parameters was designed to reduce the CE during MMS. A fuzzy PI controller was also employed to improve response times and decrease OSM tracking motion steady-state error. Finally, MATLAB/Simulink simulations were performed and experimentally validated on hard pavement. The results showed that the proposed methodology could effectively reduce CE and guarantee MMS control stability while substantially shortening response times. The proposed methodology is effective and feasible for FC MMS. [ABSTRACT FROM AUTHOR]

In this paper, a cooperative triple-phase-shift (CTPS) control for the isolated dual active bridge dc–dc converter is proposed first to eliminate the dual-dc side flow back currents. Furthermore, the current characteristics of the proposed CTPS control with the main variable (the primary side inner phase shift) tuned in two different regions are derived in detail and compared with each other. The tuning region of the main variable with the optimal current characteristics is finally determined based on the comparison results. As a result, the current stress is reduced and the efficiency is enhanced. The detailed experimental results of CTPS control verify its validity and practicability. The advantages of CTPS control are also highlighted by comparing it with some conventional phase shift controls. [ABSTRACT FROM AUTHOR]

Hybrid unmanned aerial vehicles (UAV) combine advantages of multicopters and fixed-wing planes: vertical take-off, landing, and low energy use. However, hybrid UAVs are rarely used because controller design is challenging due to its complex, mixed dynamics. In this paper, we propose a method to automate this design process by training a mode-free, model-agnostic neural network controller for hybrid UAVs. We present a neural network controller design with a novel error convolution input trained by reinforcement learning. Our controller exhibits two key features: First, it does not distinguish among flying modes, and the same controller structure can be used for copters with various dynamics. Second, our controller works for real models without any additional parameter tuning process, closing the gap between virtual simulation and real fabrication. We demonstrate the efficacy of the proposed controller both in simulation and in our custom-built hybrid UAVs (Figure 1, 8). The experiments show that the controller is robust to exploit the complex dynamics when both rotors and wings are active in flight tests. [ABSTRACT FROM AUTHOR]

This paper presents a new bandwidth tuning theory for Butterworth-response resonator filters. The presented theory shows that the bandwidth of odd-order Butterworth filters can be varied by adjusting only two interresonator coupling structures while maintaining a perfect impedance matching at the center frequency. In other words, this paper presents an analytic approach to reduce the number of tunable coupling structures when designing a bandwidth-tunable resonator filter. Theories for third- and fifth-order direct-coupled filters are discussed in detail, and it is shown that only two interresonator coupling structures are required to be tunable. In addition, for verifying the new bandwidth tuning method, a fifth-order cylindrical cavity filter has been designed, fabricated, and measured. The fabricated filter has an 11:1 bandwidth tuning range. [ABSTRACT FROM AUTHOR]

This paper is associated with an autotuning stochastic resonance (SR) approach for image enhancement on illumination variant images. This new process is being developed based on our previous works related to image enhancement by using SR through the manual tuning process. The process was performed by adding the random noise and threshold 0 in an image. The process works properly in the dark and very low contrast images as well as bright images based and mixed illumination variant images. This system works on the images with the mixture of darkness and brightness. We also present the idea of autotuning of the iteration with random noise and threshold value 0 by using the process related to the histogram calculation or mean and median. We performed various experiments on various types of images including human faces under different conditions and confirmed the effectiveness of our image enhancement technique. [ABSTRACT FROM AUTHOR]

For a system of bioethanol purification based on extractive distillation, this work addresses the problem of determining the better control configuration and the systematic tuning of the PI controllers in a framework of physical insight. The purification system is a distillation column train consisting of a preconcentration column, a dehydration column and a entrainer recovery column. To establish the control loops, a parameter called Operability Index (OI) was proposed and applied. All possible control loops were evaluated, and unlike typical works, also impurities in the product streams were considered as control outputs. The outcomes suggested that less control effort is achieved by controlling impurities than controlling purities; this means, the OI for impurities were lower than the ones for purities, and the control configuration was easily established by choosing loops of small OI. In the next step of tuning the linear PI controller for each loop, an approach of stable pole assignment was followed. Through this technique, all controllers were tuned simultaneously, and the values of the controller gains were calculated directly from the static gains and a pseudo time constant identified for every loop; this pseudo time constant corresponds to the best first order dynamics matched to the dynamics of the control output with respect to unit change of the control input. Through simulations in Aspen Plus Dynamics®, the performance of controlling impurities was illustrated and compared with the one of controlling purities, and the simultaneous tuning of controllers was demonstrated. [ABSTRACT FROM AUTHOR]

We present a sensitive, tunable radio-frequency resonator designed to detect reactive changes in nanoelectronic devices down to dilution refrigerator temperatures. The resonator incorporates GaAs varicap diodes to allow electrical tuning of the resonant frequency and the coupling to the input line. We find a resonant frequency tuning range of 8.4 MHz at 55 mK that increases to 29 MHz at 1.5 K. To assess the impact on performance of different tuning conditions, we connect a quantum dot in a silicon nanowire field-effect transistor to the resonator and measure changes in the device capacitance caused by cyclic electron tunneling. At 250 mK, we obtain an equivalent charge sensitivity of 43 μ e / Hz when the resonator and the line are impedance-matched and show that this sensitivity can be further improved to 31 μ e / Hz by re-tuning the resonator. We understand this improvement by using an equivalent circuit model and demonstrate that for maximum sensitivity to capacitance changes, in addition to impedance matching, a high-quality resonator with low parasitic capacitance is desired. [ABSTRACT FROM AUTHOR]

Highlights • residue phase compensation at 180 degrees is neither necessary nor optimal. • phase compensation and gain can be optimally computed in a coordinated way. • standard IEEE PSS tuned for a trade-off performances (damping)/robustness. • appliable to any damping actuator and for any type of oscillatory mode. Abstract One of the most used way to tune the parameters of power oscillations damping controllers (like, e.g., the power system stabilizers (PSS) of generators) is to provide a phase compensation to 180 degrees of the phase of the residues of the inter-area modes to be damped and, next, to increase the gains of the controllers in order to obtain the desired damping for the aforementioned modes. It is shown here that this way of doing is suboptimal. First, from the physical point of view, there is no a priori reason to compensate the phase to 180 degrees. Next, concerning the damping of the oscillations, when the phase compensation is computed in a coordinated way with the gain of the controller, better results are systematically obtained. This means that, in comparison with the standard way of phase compensation (to 180 degrees), this new tuning strategy provide the same damping level obtained with lower gains for the controllers (i.e., with more robust controllers) or, alternatively, higher damping levels with the same level of gains (i.e., better performances). The optimal parameters of the controllers are solutions of constrained optimization problems for the general case of several controllers tuned to damp several modes. Examples on both academic and real large-scale (the European power system model) cases are given. This result is general and can be applied to any control framework (for classic generators or more advanced (optimal) control, for local, inter-area or other oscillatory modes). [ABSTRACT FROM AUTHOR]

Abstract Nitrogen oxide (NOx) emission regulations are strengthening to reduce fine particles (particulate matter) in the East Asian, countries including Korea. In this paper, empirical evidence of exhaust gas (NOx) reductions considering the pilot fuel split ratio of a combustion-tuning methodology is provided using the full-scale gas turbine combustion test facility of the KEPCO (Korea Electric Power Cooperation) research institute. The combustion-tuning methodology confirmed in the laboratory was verified by load tests (50%, 70%, and 100% loads) for the Gunsan CCPP (combined cycle power plant) at Korea Western Power. Particularly, empirical tests of the NOx reduction effect of around 20% without the combustion instability phenomenon under a partial load were successfully carried out. The change in the fuel ratio through the tophat and pilot nozzle and the change in the combustion air volume through a bypass valve were analyzed to assess the sensitivity to the amount of NOx emission generated under actual gas turbine (Mitsubishi Hitachi Power System's GT model for power generation: 501G) operating conditions. It was also confirmed qualitatively that the trends of the NOx emission due to a change in the pilot fuel split ratio from full-scale atmospheric test results in a laboratory and actual operation data of the actual gas turbine under a 50% load were similar. Based on the reduced amount of NOx by the combustion-tuning methodology, the basic deductible savings levels for each gas turbine unit due to the exhaust gas regulation were introduced. [ABSTRACT FROM AUTHOR]

Highlights • The shaft-bending is firstly considered to the shaft-disk-blades coupling vibration problem. • The evolution mechanism relies on the changes of the mistuned features parameters. • The vibration localization phenomenon appear due to the mistuned features. • The mistuned features have not obviouse influencs on the Campbell results. Abstract The purpose of this paper is to investigate the coupling vibration characteristics of a flexible shaft-disk-blades system with mistuned features. There are some new phenomena due to the coupling effects of shaft-bending, shaft-torsion, disk-transverse and blade-bending. In this investigation, this paper mainly focuses on the influence of mistuned features of the blade's length and the stagger angle. It is found that there are four types of coupling modes: the coupling mode of shaft bending, disk transverse and blade bending (SDB), the coupling mode of shaft torsion disk transverse-blade bending (TDB), the coupling mode of disk transverse and blade bending (DB), the repeated mode of blade bending-blade bending (BB). With the effect of mistuned features, the natural frequencies and the coupling mode type will change correspondingly. With the mistuning value of blade length employed in this study, the TDB mode in the tuned system will disappear and shift into TSDB mode instead, and one of the repeated SDB modes will be replaced by STDB modes. Due to this mistuned features, the blades and disk experience a certain degree of vibration localization phenomenon. Different from the length feature, the influence of mistuning values of blade's stagger angle mainly take effect on the coupling modes. At last, by inspection on the Campbell diagrams, the influence of rotational speed on the transformation of natural frequencies is illustrated on the tuned/mistuned flexible shaft-disk-blades coupling structure. [ABSTRACT FROM AUTHOR]

In this paper, a new method was proposed with the objective of maximizing the rate of wind power integration into the electric grid. This method was based on the optimization of the parameters of the turbine governors (TGs) by means of a genetic algorithm. The tuning of TGs' parameters was formulated relying on an objective function aiming at reaching the maximum wind power penetration rate. The dynamic grid modeling consisted of synchronous machines, regulators, and wind turbines. The IEEE 14-bus modified test system was adopted to test the grid using the Power System Analysis Toolbox. The simulation results revealed that, with the optimized TGs' parameters, the rate of wind power integration improved considerably. [ABSTRACT FROM AUTHOR]

This paper devotes to design of Fuzzy Adaptive PID position Controller of servo drive of telescope's axis to tracking space objects with high accuracy. Suggested method automatically adjusts membership functions and control rules of fuzzy controller using an evolutionary algorithm. Finally, simulation and experimental results demonstrate that presented controller is effective in high-precision control due to elimination of stepping mode that may be occur in multi-mass system with nonlinear friction torque at very low tracking speed for space objects. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Saw-toothed Pt-shells coating on concave Pd NCs are successfully prepared. • Saw-toothed morphologies increase with R of the concentration of CTAB to CTAC. • Pd/Pt STNC R=4 has (3 1 0) and (4 1 0) facets. • Pd/Pt STNC R=1 and Pd/Pt STNC R=0.25 have (3 1 1) facet. • ORR activity and stability of Pd/Pt STNC R=4 /C are superior to Pt/C. Abstract Herein, a facile co-surfactant method has been reported for the synthesis of core-shell Pd/Pt saw-toothed nanocubes (Pd/Pt STNCs). In this method, saw-toothed morphologies increase with decreasing ratio (R) of the concentration of cetyltrimethylammonium bromide to cetyltrimethylammonium chloride in the synthesis solution. High-resolution transmission electron microscopy (HR-TEM) images reveal that the Pd/Pt STNC prepared using R = 4 (Pd/Pt STNC R=4) has (3 1 0) and (4 1 0) facets on its edge, whereas the Pd/Pt STNCs prepared using R = 1 (Pd/Pt STNC R=1) and 0.25 (Pd/Pt STNC R=0.25) have (3 1 1) high-index facets. Furthermore, the comparison based on electrochemical surface area (ESA) shows that carbon-supported Pd/Pt STNC R=4 used for catalysing acidic oxygen reduction exhibits a kinetic current of 0.44 mA at 0.9 V (vs. RHE), which is 1.4-times greater than that obtained for commercial Pt/C (0.31 mA). The higher activity could be caused by enriched electrons on the Pt outershell with less adsorbed Cl− ions, as confirmed by the X-ray photoelectron analyses. Accelerated durability test results show that the Pd/Pt STNC R=4 catalyst is more stable than Pt/C. [ABSTRACT FROM AUTHOR]

Highlights • SrZnO 2 has self-excitation luminescence properties. • Excitation properties of SrZnO 2 were regulated by doping Ca2+ ions. • Excitated at 374 nm, Sr 0.85 Ca 0.15 ZnO 2 :Eu3+ obtains a broad emission band. • Tunable red-emitting was realized by doping Ca2+ ions into SrZnO 2 :Eu3+. • Sr 0.85 Ca 0.15 ZnO 2 :Eu3+ obtains the red emission with 90.05% color purity. Abstract A series of Sr 1− x Ca x ZnO 2 :0.02 Eu3+ phosphors have been prepared by solid-state method. The effects of Ca2+ ions on luminescent properties of SrZnO 2 :0.02 Eu3+ have been systematically investigated by X-ray diffraction (XRD) patterns, the photoluminescence excitation and emission spectra, and International Commission on Illumination (CIE) chromaticity diagram. The red-emitting of Eu3+ doped Sr 1− x Ca x ZnO 2 phosphors can be tuned based on the host-sensitized luminescence effect, in which the maximum emission intensity and 90.05% color purity at 396 nm excitation, a broad emission band ranging from 475 to 800 nm at 374 nm excitation have been achieved in the Sr 0.85 Ca 0.15 ZnO 2 :0.02 Eu3+ sample, which demonstrate the occurrence of energy transfer from host to Eu3+ ions. Therefore, Eu3+ doped Sr 1− x Ca x ZnO 2 phosphors will become a promising candidate as a new single-host red-emitting phosphor for white LEDs applications. [ABSTRACT FROM AUTHOR]

Highlights • Tuning of velocity feedback control units through power absorption maximisation. • Experimental measure of the power flow in each control unit. • Numerical validation of the experimental results with a mobility/impedance model. • General methodology to assess performance with respect to control effort. Abstract This paper discusses the tuning of multiple decentralised velocity feedback units for broadband vibration control on a plate using inertial actuators. An analysis of the performance is presented in terms of maximising the mechanical power absorbed and of the control effort, defined by the electrical power in the control units, and the results are validated numerically. Two inertial actuators are mounted on an experimental plate, and driven with control currents proportional to the measured local velocities of the plate, collocated with the actuators. Tuning is compared by using either the measurement of kinetic energy of the plate, or the mechanical power absorbed by the control units from the plate. It is found that the mechanical power absorbed can be used as a local cost function to tune the control units, as an alternative to the kinetic energy, not only when reactive actuators are used, but also when inertial actuators are in use. In this way, the tuning process is greatly simplified, since the mechanical power absorbed can be measured directly from the feedback velocity signal and a knowledge of the actuators dynamics, without further information on the plate dynamics. The optimal gain for each unit is found to be reasonably independent of the gain implemented on the other unit. This implies that the system is robust against failure of a unit, since the other would still be optimally tuned. However, this tuning process depends on many factors, such as the type, position and number of control units implemented, and a comparison between different active control solutions, with respect to the optimal feedback gains only is not practical. For this reason, the measure of the electrical power, required by the control system, is suggested as a direct estimation of the control effort. To give an example of the proposed approach, the performance of the two control units is compared with the case in which only one unit at the time is active. The two-channel architecture is found not only to outperform the single-channel one in terms of vibration reduction, but also in terms of consumed electrical power. When the two channels are active, more than 8 dB broadband reduction is measured, and the consumed electrical power is found to be similar to the one consumed when only one unit is operating, which is optimally tuned. [ABSTRACT FROM AUTHOR]

Abstract In this study, we examined the effect of pre-existing dislocation structures in a face-centered cubic γ-phase on strain-induced martensitic transformation (SIMT) to produce a hexagonal close-packed ε-phase in a hot-rolled biomedical Co–Cr–Mo alloy. The as-rolled microstructure was characterized by numerous dislocations as well as stacking faults and deformation twins. SIMT occurred just after macroscopic yielding in tensile deformation. Using synchrotron X-ray diffraction line-profile analysis, we successfully captured the nucleation of ε-martensite during tensile deformation in terms of structural evolution in the surrounding γ-matrix: many dislocations that were introduced into the γ-matrix during the hot-rolling process were consumed to produce ε-martensite, together with strong interactions between dislocations in the γ-matrix. As a result, the SIMT behavior during tensile deformation was accelerated through the consumption of these lattice defects, and the nucleation sites for the SIMT ε-phase transformed into intergranular regions upon hot rolling. Consequently, the hot-rolled Co–Cr–Mo alloy simultaneously exhibited an enhanced strain hardening and a high yield strength. The results of this study suggest the possibility of a novel approach for controlling the γ → ε SIMT behavior, and ultimately, the performance of the alloy in service by manipulating the initial dislocation structures. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

In this study, a novel data-driven direct automatic tuning scheme is proposed for the general form of fixed-structure digital controllers of hybrid systems. The controller is directly auto-tuned while it interacts with the real plant; no modelling or plant identification procedure is involved. The auto-tuning problem is formulated as a controller parameter optimisation problem, which is solved using a quasi-Newton method. A new method for calculating the gradient of the objective function from closedloop experiment data is proposed to reduce the sensitivity to the initial values of the parameters. Domain knowledge of controller design based on pole placement and internal model principle is introduced as a priori information to further improve the performance of the auto-tuning. Numerical simulations are conducted to demonstrate the effectiveness of the proposed scheme and performances of different objective functions are evaluated. The performance of the proposed scheme is compared with the standard relay feedback and iterative feedback tuning methods. Reliable controllers can be obtained automatically by using the proposed scheme; the only remaining task of the control engineer is to estimate the order of the plant by counting the number of independent energy storage elements. [ABSTRACT FROM AUTHOR]

Abstract A series of Eu ions activated in Sr 9-x La 1+x (PO 4) 7-x (SiO 4) x (x = 1, 3, 5, 7) prepared from powder-based precursors have been investigated firstly. The luminescence evolution in response to crystal structure variations was investigated using X-ray diffraction, Rietveld refinement, photoluminescence (PL) and PL excitation spectra, and CIE coordination. As x increased from 1 to 7, the crystal structure changed from whitlockite to apatite, and the ligand bonds between the Eu2+ and O2− ions became shorter. Both crystal structures include two different kinds of Eu sites. The peak positions of the PL bands caused by the Eu2+ ions shifted from 416 nm to 505 nm as x increased with 365 nm excitation. This shift is mainly attributed to the fact that Eu2+ ions prefer higher energy sites in the whitlockite structure and lower energy sites in the apatite structure. The red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. Under the various excitation wavelengths, the PL spectra changed tremendously. CIE coordination measurements and 2D PL contour map profiles demonstrated that the phosphor series could be tuned from blue to red by adjusting x, and a tunable phosphor covering full color could be achieved by adjusting the excitation wavelength. Moreover, the PL emission from the x = 1 sample provided an internal quantum efficiency of up to 100%. Graphical abstract Image 1 Highlights • The emission spectra were clarified by Van Uitert equation and crystal field strength equation. • The IQE of the Sr 8 La 2 (PO 4) 6 (SiO4): Eu2+ (for x = 1) phosphor was found to be up to 100%. • By adjusting x with a fixed excitation wavelength, the emission tuned from blue to red. • Fabricated pc-LEDs achieved from cold white to warm white. [ABSTRACT FROM AUTHOR]

This paper proposes a robust fractional-order controller for DC servomotor using internal model control and CRONE (Commande Robuste d'Ordre Non Entier) principle. The controller acquires a PID (proportional-integral-derivative) form followed by a fractional-order integrator. Unlike the conventional fractional-order PID controller which demands five tuning parameters, the proposed scheme has only two tuning parameters which can be obtained on the basis of desired gain crossover frequency and phase margin. For speed control problem, the performance of the proposed controller is studied on hardware set up called precision modular servo system. The proposed controller outperforms in terms of robustness and optimality when compared with controllers designed by integer-order technique. Furthermore, the proposed scheme is applied for position control problem and validated on QUBE-Servo 2 set up. [ABSTRACT FROM AUTHOR]

An innovative plastic deformation method is proposed to tune metal-based MEMS devices after fabrication. The plastic deformation is a well-known failure mechanism in MEMS devices, which includes a phenomenon that the devices do not return original position after repeated actuation. Here, in contrast to this common experience, we exploit the plastic deformation for the first time to tune the performance of MEMS devices, by producing deliberate, controlled plastic deformation with the help of Joule heating. The proposed plastic deformation method is precisely and predictably controlled by the model we developed here, and it was successfully demonstrated and evaluated using a fabricated MEMS device. Unlike conventional plastic deformation methods, the proposed method was accomplished solely by electrical control, which means that the method can be employed in integrated devices. Tuning resolution was demonstrated at a 10-nm level, which is remarkably smaller than that of conventional plastic deformation methods, where the tuning resolution is typically several micrometers. We confirmed that the proposed method does not deteriorate the basic performance of the fabricated MEMS devices. Finally, we proposed and demonstrated a method for calibrating MEMS devices after fabrication and suggested an interesting application, which is recovering the performance of aged MEMS devices. [2017-0129] [ABSTRACT FROM AUTHOR]

In this article, a novel graphical tuning method is proposed to determine all feasible parameters of PID controller satisfying multiple objectives including disturbance rejection for a wide range of processes. The proposed method is based on a graphical method and the obtained parameters can satisfy a given analyzing reference to disturbance ratio (RDR) index, which is used in this paper to evaluate the disturbance rejection performance. In a similar way, all the parameters satisfying transient state specification of set-point tracking response and robustness specification are determined. As a result, the intersection region presents all available parameters that can provide multiple objectives. This paper proposes an alternative way to optimize the PID controller satisfying multiple objectives. Since no optimization algorithm is used, the proposed method is simpler than PID design methods using optimization method. Three examples are given to demonstrate the flexibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract The increasing amount of researches have proven the advantages of fractional order PID controllers. For fractional order PI (FO-PI) controller, the classical tuning approach is based on specifying a certain gain crossover frequency, a phase margin and a robustness to plants gain variations, it can be implemented by applying a series of open-loop experiments without an accurate process model. Additionally, the performance optimization is a widely used auto-tuning method, it searches online for the controller parameters that minimize a cost function which quantifies the closed-loop performance. Based on extremum seeking (ES) algorithm, a novel indirect optimization scheme for tuning a FO-PI controller which combines the regular ES optimization with the classical tuning approach is proposed in this paper. Instead of optimizing the controller parameters directly, we parametrize all the controllers leading to the given performance specifications (cross-over freq, phase margin, iso-damping) and then do the optimization of the cross-over freq and phase margin to achieve the best step-response performance. Simulation and experimental results demonstrate that the proposed ES optimization scheme can achieve a great balance between robustness and performance. [ABSTRACT FROM AUTHOR]

Abstract Today, fractional order proportional integration derivative (FO-PID) controllers have attracted much attention from academia and industry. Despite FO-PID controllers outperforming integer order (IO) ones in many cases, the latter continues to dominate industrial utilization. One of the big barriers which confine adoption of FO-PID controllers is the complexity of the current tuning methods for industrial application. In this paper, a practical tuning method for FO-PID controllers is introduced. In this line, classical loop-shaping tools are utilized to propose this new simple tuning rule. A rule of thumb and a guideline are given for non-expert and industrial users for controlling motion systems. Finally, the tuning method is validated in a high-tech precision positioning system. [ABSTRACT FROM AUTHOR]

Highlights • This paper designs a method to optimize the PID settings in a microbial fermenter. • Best-fit process models are obtained and the PID parameters are dynamically optimized. • Optimal settings are found for both set-point tracking and disturbance rejection. • The PID optimization algorithm is demonstrated to work successfully in experiments. Abstract Vaccine development comprises multiple stages, the first of which involves cultivating an organism in a microbial fermenter to produce a vaccine product. In order to ensure the optimal synthesis of the vaccine product, it is necessary to maintain adequate control of the dissolved oxygen (dO 2), which is required for the organism to grow and survive. Our work is concerned with controlling the dissolved oxygen in a biological fermenter using a PID (Proportional-Integral-Derivative) Controller. The product from this fermenter is used to create the immunization for a medical illness. However, the present configuration of the PID Controller is inadequate for maintaining the dissolved oxygen at the desired level of 35% relative to saturation. This inadequacy results in violent dO 2 oscillations which compromise the quality of the product. To solve this issue, we use open-loop experimental data to develop empirical transfer-function models of the control process for dissolved oxygen. Then, we apply an optimization algorithm for the PID Controller to obtain the proportional, integral, and derivative gains that would best regulate the dissolved oxygen in the fermenter. The parameters obtained from this algorithm are applied experimentally to the biological fermenter set-up and the results are used to demonstrate that the PID optimization algorithm provides controller settings which successfully regulate the dissolved oxygen. [ABSTRACT FROM AUTHOR]

Abstract ParamILS, I-Race and Evoca are well-known tuning methods designed to search quality parameter calibrations for metaheuristic algorithms. The set-up of parameter search space can strongly affect the performance of tuning methods. In this work we study how the parameter search definitions affect the quality of parameter calibrations delivered by these tuners. An experimental evaluation using two well known metaheuristic algorithms and a real life case is presented. We also provide some guidelines to consider when defining parameters search spaces according to the tuner used in order to obtain the best performance they can find. [ABSTRACT FROM AUTHOR]

The transmission loss (TL) curve of a simple expansion chamber (SEC) is characterized by periodic domes. Theory of double tuning of the extended-inlet extended-outlet chamber consists in dimensioning the extended inlet (EI) and extended outlet (EO) at half and quarter chamber length (minus the end corrections) so that three-fourths of the troughs of the SEC-TL curve are tuned out, by the quarter-wave resonances of the EI and EO. However, this does not explain the shape and overall lifting of the resulting TL curve. In the present article, an analytical expression has been derived for TL of the double-tuned side-inlet side-outlet (SISO) muffler. Comparison of this expression with that of the SEC muffler explains the entire shape of the TL curve and reveals two interesting and useful implications of double tuning. Barring sharp peaks atHelmholtz numbers of p, 2p and 3p, the base TL curve of the double-tuned chamber (DTC) is similar to that of the corresponding SEC, with effective chamber length reduced to one-fourth and the area expansion ratio increased to fourfold. Consequently, one dome of the DTC-TL spans over four domes of the SEC-TL, and the new wider dome stands 12 dB higher than the domes of the corresponding SEC-TL curve. The 1-D predictions have been validated against the 3-D FEM simulations. Exact matching of the locations of the first three sharp peaks of the TL curves indicates that no end corrections would apply to the quarter-wave resonators of the SISO muffler configuration. [ABSTRACT FROM AUTHOR]

This paper describes the working principle, the design, and the characterization of a three-axis frequency-modulated MEMS accelerometer, in which the differential frequency readout is performed through a novel time-switched approach. The proposed methodology is based on a double sampling of the oscillation frequency of a single resonator, consecutively biased in two different configurations in time. This technique enables to avoid offset thermal drift contributions typical of differential resonant accelerometers based on two distinct resonators with unavoidable mismatch in the temperature coefficient of frequency (TCf). Alternatively, a residual TCf offset drift component can be tuned to counterbalance other drift sources (e.g., stress-related), allowing a complete cancellation of the zero-g-offset (ZGO) thermal drift. Experiments on various samples report repeatable sub- $50~\mu \text{g}$ /K thermal drift without post-acquisition corrections, with a full-scale higher than $32~g$ at a $100~\mu \text{g}/\sqrt {\text {Hz}}$ consumer-grade resolution. [2018-0089] [ABSTRACT FROM AUTHOR]

In a superconducting photon detector, the effective transition to the normal state can be induced by the instability of the flux flow regime. Indeed, in the presence of self-magnetic field, the local suppression of superconductivity induced by photon absorption determines vortex nucleation and flux flow regime, which can make the superconducting state unstable. Understanding such instability can boost the performances of those superconducting devices based on this resistive switching. Here, we present the study of the geometry influence on such instability in NbN and NbTiN ultrathin films. Despite the same patterned microbridge geometry, the two superconductors show different behaviors at very low applied magnetic fields. A comparison with other superconductors outlines the possibility to tune the resistive switching by geometry effects in interesting materials for devices applications. Finally, we also report the influence of the cooling environment on the electric critical power in superconducting thin films. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a parameters tuning method based on the genetic algorithm (GA) for an active disturbance rejection control (ADRC) of a three-axis inertially stabilized platform (ISP) with imaging sensors. To improve the stabilization accuracy and robustness of an aerial ISP under multi-source disturbances environment, an ADRC control scheme is first proposed. Then, to accurately identify and tune the parameters in the ADRC controller, a GA-based parameters tuning method is proposed. In this way, the performance of the ADRC is superior to the empirical method. To validate the proposed method, the simulations and experiments are carried out. The results show that the proposed ADRC with GA-based parameters tuning method has significant disturbance rejection ability which can improve the stabilization accuracy obviously. Compared with the ADRC with empirically tuning method, the stabilization error (RMS) under movable base is decreased up to 50.09%. Highlights • An ADRC control scheme is proposed to improve the stabilization accuracy and disturbance rejection ability of an ISP. • A GA-based parameters tuning method is proposed to accurately identify and tune the parameters of the ADRC controller. • The empirical parameters tuning method and the proposed GA-based method are both applied in the work as a comparison. • Simulations and experiments are carried out to validate the proposed method. [ABSTRACT FROM AUTHOR]

Abstract It is recognized that disturbance rejection is much more important than set-point tracking for many process control applications, leading set-point tracking to a secondary level of interest. In this paper a proposal for robust tuning of PI/PID controllers designed under the direct synthesis for load disturbance (DS-d) approach is presented. As with the IMC- like approaches, the resulting DS-d tunings are expressed in terms of a unique parameter that determines the desired speed of response of the regulatory behavior. Even at first sight it may seem quite simple, there is no known guide on how to select such parameter in order to achieve some desired robustness. As it will be shown, for some process dynamics, this selection is not as simple as it may seem. Tuning expressions for the most common types of process models are provided such that the closed loop time constant is the fastest one that allows to reach the desired robustness. Simulation examples show the application of the suggested tuning. Highlights • The robustness analysis of the PI/PID tuning by using the Direct Synthesis dor load disturbance approach. • To provide selection of the closed-loop to open-loop time constants ratio in order to achieve a desired robustness. • To provide robust tuning for load disturbance for the most common dynamics present in process control problems. [ABSTRACT FROM AUTHOR]

Radiation efficiencies of modal current densities distributed on a spherical shell are evaluated in terms of dissipation factor. The presented approach is rigorous, yet simple and straightforward, leading to closed-form expressions. The same approach is utilized for a two-layered shell and the results are compared with other models existing in the literature. Discrepancies in this comparison are reported and reasons are analyzed. Finally, it is demonstrated that radiation efficiency potentially benefits from the use of internal volume, which contrasts with the case of the radiation $Q$ -factor. [ABSTRACT FROM AUTHOR]

Abstract In robotics or machining, task quality is strongly linked to servo tuning. Indeed, geometrical and dynamic behavior of the mechanical structure could be degraded when a coarse tuning is achieved. Several P/PI or PID tuning methods can be used but generally uncorrelated with industrial context or mechanical considerations. In this paper, we propose a generic tuning method based on dynamic modeling of the mechanical structure and model parameters experimental identification. Therefore, the proposed tuning is adapted to the real dynamic behavior of the mechanical structure under task load while being sufficiently simple to be implemented in an industrial context. The method is illustrated on a vertical axis. Highlights • This paper deals with a new tuning method adapted to robots and machines with regards to the task and structure specificities. • This tuning method is validated experimentally on a vertical axis. • The tuning method is based on the mechanical structure dynamic modeling. • The dynamic parameters are identified under task solicitations to ensure reliability with the real behavior of the machine. [ABSTRACT FROM AUTHOR]