Main Control Parameters Research Articles

Motor control characteristics for circular tracking movements of human wrist

This paper investigates motor characteristics during circular tracking movements of human wrist. Ten subjects performed a visually guided target tracking task using two degrees-of-freedom wrist movements as a tracer. Based on trajectories of the tracer and the target, three control parameters in polar coordinates were considered: R error as an evaluation of the circular movement performance, theta error of the position-control precision, and omega error of the velocity-control precision. We then examined the influence of three different speeds (0.05, 0.1, and 0.2 Hz) and visibility of the target on the three parameters to observe changes in control strategy. The theta error particularly demonstrated that subjects were more dependent on position control for the lower tracking speed of 0.05 Hz with a visible target, where the highest percentage increase of 210.6% in theta errors from the target visible to the target invisible regions was reported. However, as the target speed increases, the subjects concentrated more on the velocity of the target as a main control parameter, and a minimum percentage decrease of 9.52% in the omega error appeared from target visible to target invisible regions for 0.2 Hz. The results suggest that velocity control is more dominant during target invisible or fast tracking task.

Turbulent thermal convection driven by heated inertial particles

The heating of particles in a dilute suspension, for instance by radiation, chemical reactions or radioactivity, leads to local temperature fluctuations in the fluid due to the non-uniformity of the disperse phase. In the presence of a gravity field, the fluid is set in motion by the resulting buoyancy forces. When the particle density is different than that of the fluid, the fluid motion alters the spatial distribution of the particles and possibly strengthens their concentration inhomogeneities. This in turn causes more intense local heating. Direct numerical simulations in the Boussinesq limit show this feedback loop. Various regimes are identified depending on the particle inertia. For very small particle inertia, the macroscopic behaviour of the system is the result of many thermal plumes that are generated independently of each other. For significant particle inertia, clusters of particles are observed and their dynamics controls the flow. The emergence of very intermittent turbulent fluctuations shows that the flow is influenced by the larger structures (turbulent convection) as well as by the small-scale dynamics that affect particle segregation and thus the flow forcing. Assuming thermal equilibrium between the particles and the fluid (i.e. infinitely fast thermal relaxation of the particle), we investigate the evolution of statistical observables with the change of the main control parameters (namely the particle number density, the particle inertia and the domain size), and propose a scaling argument for these trends. Concerning the energy density in the spectral space, it is observed that the turbulent energy and temperature spectra follow a power law, the exponent of which varies continuously with the Stokes number. Furthermore, the study of the spectra of the temperature and momentum forcing (and thus of the concentration/temperature and velocity/temperature correlations) gives strong support to the proposed feedback loop mechanism. We then discuss the intermittency of the flow, and analyse the effect of relaxing some of the simplifying assumptions, thus assessing the relevance of the original studied configuration.

Electrospray deposition of SnO2 films from precursor solution

The electrospray deposition (ESD) of SnO2 films from SnCl4.5H2O precursor solution was performed for gas sensor applications. Deposition time, solution flow rate and solution concentration were the main control parameters in the ESD process. The morphological properties of the deposited films were characterised by scanning electron microscopy. X-ray diffraction and energy dispersive X-ray analyses were employed to confirm the crystal phases and composition of the films. The best coatings with an island of particle agglomerates were observed at a flow rate of 0.12 ml min−1, for 60 min, and at a 0.05M concentration. The crystallisation of SnO2 films was observed at 650°C. The grain size and surface morphology of the films were influenced by the sol concentrations. Larger grain size and cracked surface were observed by increasing the sol concentration. The film thickness of 6 µm and a grain size of less than 100 nm were achieved.

Are subversion and conflict component parts of social cohesion?

This article focuses on the development of control mechanisms of open pit mine robotized transport system. Method for the state of the technological roads identification with the use of fuzzy inference mechanisms is discussed.The structure of the control system is presented. The possibilities of the use of telemetry data for a wide range of important technological problems, which, anyway, are reduced to problems of interpretation of the data, object identification, forecasting of parameters and the interaction of robotic agents control are discussed. The examples of the formal setting of some of these problems which based on the soft computing are presented. Considered in detail the problem of identification of the open pit mine roadway. The procedure for organizing and conducting dump truck onboard experiments is described. The features of the main control parameters are analyzed. The mechanism of using the telemetry data processing in common with fuzzy inference tools is presented. The main stages of the experiment telemetry data processing are described.

Cultivation and characteristics of partial nitrification granular sludge in a sequencing batch reactor inoculated with heterotrophic granules.

The aim of this study was to develop a simple operation strategy for the cultivation of partial nitrification granules (PNGs) treating an autotrophic medium. For this strategy, aerobic granular sludge adapted to high concentration organics removal was seeded in a sequencing batch reactor (SBR) with a height/diameter ratio of 3.8, and the ratio of organics to the ammonia nitrogen-loading rate (C/N ratio) in the influent was employed as the main control parameter to start up the partial nitrification process. After 86days of operation, the nitrite accumulation rate reached 1.44kg/(m3day) in the SBR, and the removal efficiency of ammonia nitrogen (NH4+-N) was over 95%. The PNGs showed a dense and compact structure, with an excellent settling ability, a typical extracellular polymeric substance (EPS) composition, and a high ammonia oxidation activity. The high-throughput pyrosequencing results indicated that the microbial community structure in the granules was significantly influenced by the C/N ratio, and ammonia-oxidizing bacteria (AOB), including the r-strategist Nitrosomonas and k-strategist Nitrosospira genre, which accounted for approximately 40% of the total biomass at the end of operation. The effective suppression of nitrite-oxidizing bacteria (NOB) growth was attributed to oxygen competition on the granular surface among functional bacteria, as well as the high free ammonia or free nitrous acid concentrations during the aeration period.

Parametric study on interaction of blower and back pressure control valve for a 80-kW class PEM fuel cell vehicle

Numerical study on the performance of the polymer electrolyte membrane (PEM) fuel cell vehicle with variable operating pressure was conducted to investigate the effect of blower and backpressure control valve. We conducted system level modeling for PEM fuel cell vehicle to predict its performance, where the model is based on the commercial fuel cell vehicle manufactured by Hyundai-Kia Motors and thus is validated against the real driving data. We considered most parts of PEM fuel cell vehicle powertrain, i.e. blower, membrane humidifier, and backpressure control valve at cathode, hydrogen recirculation system using ejector at anode, and the system for refrigeration and air conditioning. In building such a large system model, most of the sub system models were developed based on either zero- or one-dimensional approach, but still capturing critical physical phenomena in each device. Among these components, we focused on the effect of blower and backpressure control valve in cathode side, since these are the main control parameters in the aforementioned vehicle to influence the operating characteristics of the fuel cell stack and thus the performance of the vehicle. From the system modeling results, as the rotation speed of the blower increases, the stoichiometric number for cathodic air becomes higher and the relative humidity becomes lower. When pressure is higher, power generation from stack is proportional to stoichiometric number, however, it has greatly influence on relative humidity, and the variation of system performance is similar to that of stack. In case of the backpressure control valve, the stoichiometric number is higher and the relative humidity is lower, when back pressure is low. This change begins to reduce system power. In the end, we developed the performance curve based on the blower RPM and the valve angle, at various vehicle speeds. The proposed performance curve could provide a useful means to understand overall operating characteristics of the fuel cell vehicle.

Обеспечение единства измерений параметров вибрации при технической эксплуатации воздушных судов

In this article we are talking about how to ensure the unity of measurements of vibration parameters in the technical operation of aircraft. In air transport, the main controlled parameters of vibration in flight are vibration speed, vibration acceleration or vibration overload. They are particularly informative for aircraft with turboprop engines, as well as helicopters, which – because of the design features-the vibration is much higher than on aircraft with turbojet engines.

Resolving the Physical Origin of Octahedral Tilting in Halide Perovskites

Hybrid perovskites are currently the fastest growing photovoltaic technology, having reached a solar cell efficiency of over 20%. One possible strategy to further improve the efficiency of perovskite solar cells is to tune the degree of octahedral tilting of the halide frame, since this in turn affects the optical band gap and carrier effective masses. It is commonly accepted that the ion sizes are the main control parameter influencing the degree of tilting in perovskites. Here we re-examine the origin of octahedral tilts in halide perovskites from systematic first-principles calculations. We find that while steric effects dominate the tilt magnitude in inorganic halides, hydrogen bonding between an organic A-cation and the halide frame plays a significant role in hybrids. For example, in the case of MAPbI3, our calculations suggest that, without the contribution from hydrogen bonding, the octahedra would not tilt at all. These results demonstrate that tuning the degree of hydrogen bonding can be used as...

Simulation of an Inlet Structure of an Implantable Axial Blood Pump

The article presents a mathematical model of blood flow in the inlet apparatus of an axial pump to support the ventricle. The inlet apparatus includes a curved cannula and a fixed flow straightener with three or four blades. The main control parameters are the length of the inlet portion of the cannula, the length of the outlet portion of the cannula, the inner diameter, the bending angle of the cannula, and the radius of the knee. Flow velocity at the wall is considered to be zero. The flow of blood is considered to be stationary; transient processes are not considered. Blood is considered to be a single-phase incompressible viscous Newtonian fluid. The study aims at identifying the unevenness of the flow incident on the rotor blades and at identifying stagnation zones. According to the results of calculations with various geometrical parameters, a divider is installed in the inlet apparatus model to address identified effects. Variable parameters of the divider are the radius of curvature and the length of the straight section.

Different Flame Patterns Linked With Swirling Injector Interactions in an Annular Combustor

Experiments in cold and reactive conditions carried out in linear arrays of injectors indicate that the flows established by neighboring injectors exhibit alternating patterns if the distance between two injectors is too small (see, for example, ASME-GT2013-94280, GT2014-25094, and GT2015-42509). This issue is investigated in this article by making use of a recently developed annular combustion chamber (ACC). This device designated as MICCA is equipped with multiple swirling injectors and its side walls are made of quartz providing full optical access to the flame region, thus allowing detailed studies of the combustion region structure and dynamics. Experiments reported in this article rely on direct observations of the flame region through light emission imaging using two standard cameras and an intensified high-speed CMOS camera. The data gathered indicate that interactions between successive injectors give rise to patterns of flames which exhibit an alternate geometry where one flame has a relatively low expansion angle while the next spreads sideways. This pattern is then repeated with a period which corresponds to twice the injector spacing. Such arrangements arise when the angle of the cup used as the end-piece of each injector exceeds a critical value. The effects of mass flow rate, equivalence ratio, and injector offset are also investigated. It is shown that the angle which defines the cup opening is the main control parameter. It is also found that when this angle exceeds a certain value and when the laminar burning velocity is fast enough, the flame pattern switches in an unsteady manner between two possible configurations. It is shown that these alternating flame patterns lead to alternating heat release rate distributions and inhomogeneous heat transfer to the chamber walls featuring a helicoidal pattern. Conditions leading to alternating flame patterns are finally discussed by making use of a recent flow regime diagram.

Mathematical modeling of di-ethyl-hexyl-sebacate nanoparticle formation in a free turbulent jet under high nucleation rate conditions

Mathematical modeling of di-ethyl-hexyl-sebacate (DEHS) nanoparticle formation due to homogeneous nucleation, condensation and coagulation in a hot free turbulent jet issuing into a colder environment is performed. The Reynolds-averaged Navier–Stokes equations are used to describe the fluid flow. The aerosol dynamics is treated by transforming the general dynamic equation into moment equations which are closed by assuming a lognormal shape of the particle size distribution. The contribution of condensation and coagulation to particle formation in the case of high saturation ratios and nucleation rates is studied. The sensitivity of the model to existing approximations of the vapor saturation pressure curve and the ambient temperatures is analyzed. The influence of the main control parameters of the system, such as vapor saturation temperature and nozzle exit velocity, on the aerosol characteristics formed in the turbulent jet is investigated.

Multidisciplinary Assessment of the Control of the Propellers of a Pusher Geared Open Rotor—Part I: Zero-Dimensional Performance Model for Counter-Rotating Propellers

Due to their high propulsive efficiency, counter-rotating open rotors (CRORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional high bypass ratio turbofans. However, this novel engine architecture presents many design and operational challenges both at engine and aircraft level. The assessment of the impact of the main low-pressure preliminary design and control parameters of CRORs on mission fuel burn, certification noise, and emissions is necessary at preliminary design stages in order to identify optimum design regions. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational, or regulatory constraints. The required preliminary design simulation tools should ideally be 0D or 1D (for computational purposes) and should capture the impact of the independent variation of the main low-pressure system design and control variables, such as the number of blades, diameter and rotational speed of each propeller, the spacing between the propellers, and the torque ratio (TR) of the gearbox or the counter-rotating turbine (CRT), among others. From a performance point of view, counter-rotating propellers (CRPs) have historically been modeled as single propellers. Such a performance model does not provide the required flexibility for a detailed design and control study. Part I of this two-part publication presents a novel 0D performance model for CRPs allowing an independent definition of the design and operation of each of the propellers. It is based on the classical low-speed performance model for individual propellers, the interactions between them, and a compressibility correction which is applied to both propellers. The proposed model was verified with publicly available wind tunnel test data from NASA and was judged to be suitable for preliminary design studies of geared and direct drive open rotors. The model has to be further verified with high-speed wind tunnel test data of highly loaded propellers, which was not found in the public domain. In Part II, the novel CRP model is used to produce a performance model of a geared open rotor (GOR) engine with a 10% clipped propeller designed for a 160 PAX and 5700 NM aircraft. This engine model is first used to study the impact of the control of the propellers on the engine specific fuel consumption (SFC). Subsequently, it was integrated in a multidisciplinary simulation platform to study the impact of the control of the propellers on engine weight, certification noise, and NOx emission.

Multidisciplinary Assessment of the Control of the Propellers of a Pusher Geared Open Rotor—Part II: Impact on Fuel Consumption, Engine Weight, Certification Noise, and NOx Emissions

Due to their high propulsive efficiency, counter-rotating open rotors (CRORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional high bypass ratio turbofans. However, this novel engine architecture presents many design and operational challenges both at engine and aircraft level. The assessment of the impact of the main low-pressure preliminary design and control parameters of CRORs on mission fuel burn, certification noise, and emissions is necessary at preliminary design stages in order to identify optimum design regions. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational, or regulatory constraints. Part I of this two-part publication presents a novel 0D performance model for counter-rotating propellers (CRPs) allowing an independent definition of the design and operation of each of the propellers. In Part II, the novel CRP model is used to create an engine performance model of a geared open rotor (GOR). This engine model is integrated in a multidisciplinary simulation platform which was used to assess the impact of the control of the propellers, on specific fuel consumption (SFC), engine weight, certification noise, and NOx emission, for a GOR with a 10% clipped rear propeller designed for a 160 PAX and 5700 NM aircraft. The main conclusions of the study are: (1) Minimum SFC control schedules were identified for climb, cruise, and descent (high-rotational speeds for high thrust and low-rotational speeds for low thrust), (2) SFC reductions up to 2% in cruise and 23% in descent can be achieved by using the minimum SFC control. However, the relatively high SFC reductions in descent SFC result in ∼3.5% fuel saving for a 500 NM and ∼0.7% fuel saving for a full range mission, (3) at least 2–3 dB noise reductions for both sideline and flyover can be achieved by reducing the rotational speeds of the propellers at a cost of ∼6% increase of landing and takeoff cycle (LTO) NOx and 10 K increase in turbine entry temperature, (4) approach noise can be reduced by at least 2 dB by reducing CRP rotational speeds with an associated reduction of ∼0.6% in LTO NOx, and (5) the control of the CRP at takeoff has a large impact on differential planetary gearbox (DPGB) weight, but it is almost identical in magnitude and opposite to the change in low-pressure turbine (LPT) and CRP weight. Consequently, the control of the CRP at takeoff has a negligible impact in overall engine weight.

Структура смежных течений у нагретой границы жидкости и пористой среды

We consider a structure of laminar convective boundary layer near the heated interface between the homogeneous liquid and Brinkman porous medium is saturated with the same liquid. The interface is heated uniformly. It has the constant temperature. We get the self-similar form of the convection equations in the boundary layer approximation. Also, we assume the power-law dependence of the medium permeability on the longitudinal coordinate. The self-similar profiles of the velocity and temperature in the both media are calculated with the different values of the liquid parameters, heat intensity and porous media properties. The velocity maximum always places in the uniform liquid layer. The self-similar solutions for velocity and temperature have a weak dependence on the heating intensity and porous medium parameters. Therefore, the obtained solution can be considered as universal in the first approximation. The dependencies of flow velocity on the control parameters in characteristic points are obtained. They are maximum velocity position and the interface between media. The flow velocity is almost proportional to the interface temperature. The main control parameter is the Prandtl number. Its’ growth leads to the flow deceleration and viscous boundary layer expansion. Received 14.10.2016; accepted 10.11.2016

Power plant efficiency improvement by optimizing main influential control parameters

Power plant efficiency improvement by optimizing main influential control parameters

Remote synchronization of amplitudes across an experimental ring of non-linear oscillators.

In this paper, the emergence of remote synchronization in a ring of 32 unidirectionally coupled non-linear oscillators is reported. Each oscillator consists of 3 negative voltage gain stages connected in a loop to which two integrators are superimposed and receives input from its preceding neighbour via a "mixing" stage whose gains form the main system control parameters. Collective behaviour of the network is investigated numerically and experimentally, based on a custom-designed circuit board featuring 32 field-programmable analog arrays. A diverse set of synchronization patterns is observed depending on the control parameters. While phase synchronization ensues globally, albeit imperfectly, for certain control parameter values, amplitudes delineate subsets of non-adjacent but preferentially synchronized nodes; this cannot be trivially explained by synchronization paths along sequences of structurally connected nodes and is therefore interpreted as representing a form of remote synchronization. Complex topology of functional synchronization thus emerges from underlying elementary structural connectivity. In addition to the Kuramoto order parameter and cross-correlation coefficient, other synchronization measures are considered, and preliminary findings suggest that generalized synchronization may identify functional relationships across nodes otherwise not visible. Further work elucidating the mechanism underlying this observation of remote synchronization is necessary, to support which experimental data and board design materials have been made freely downloadable.

Modeling of heat and high viscous fluid distributions with variable viscosity in a permeable channel

The flow field under study is characterized by velocity components, temperature and pressure in non-dimensional formulation. The flow is driven by suction through the horizontal channel with permeable walls fixed at different temperatures. In order to ascertain a better understanding of the dynamic behavior of the flow, the Navier-Stokes equations and the energy equation are solved concurrently applying a similarity transformation technique. The hydrodynamic structures obtained from the numerical integration include flow reversal or backward flow, collision zones due to the coexistence of wall suction and flow reversal inside the channel, the inflection through temperature distribution, the growth of thermal gradients near the walls, and the sensitivity of normal pressure gradients to the difference of temperatures at boundaries. These hydrodynamic structures are investigated considering the influences of the Peclet number P and the sensitivity of viscosity to thermal variations α which are the main control parameters of the problem.

Snap buckling of a confined thin elastic sheet

A growing or compressed thin elastic sheet adhered to a rigid substrate can exhibit a buckling instability, forming an inward hump. Our study shows that the strip morphology depends on the delicate balance between the compression energy and the bending energy. We find that this instability is a first-order phase transition between the adhered solution and the buckled solution whose main control parameter is related to the sheet stretchability. In the nearly unstretchable regime, we provide an analytic expression for the critical threshold. Compressibility is the key assumption which allows us to resolve the apparent paradox of an unbounded pressure exerted on the external wall by a confined flexible loop.

Bare-bones imperialist competitive algorithm for a compensatory neural fuzzy controller

This study proposes a bare-bones imperialist competitive algorithm (BBICA) for a compensatory neural fuzzy controller in order to solve prediction problems and nonlinear control system problems. In the proposed BBICA, the population is divided into two types: imperialists and colonies. The purpose is that the cultures of colonies and societies can be similar to their empires. Moving colonies toward their relevant imperialist refers the assimilation policy. This study focuses on improving and exploring the process of assimilation. In the assimilation policy, there are two main control parameters for adjusting the direction of motion of colonies, i.e., location and angle. This study proposes the BBICA in order to reduce the use of the control parameters. Therefore, the proposed BBICA adopts a Gaussian distribution to improve the assimilation policy and the exploration ability of the global solution. Finally, the experimental results show that the proposed BBICA better approximates the global optimal solution and that it has faster convergence compared with other methods.

Simulations of granular bed erosion due to a mildly turbulent shear flow

ABSTRACTThree-dimensional, time-dependent simulations of the erosion of a granular bed consisting of monosized, non-cohesive spherical particles are reported. The simulations fully resolve the turbulence and the flow around each of the spheres (particle-resolved, direct simulations). The erosion is due to the turbulent flow of a Newtonian liquid in a planar channel with a Reynolds number based on wall shear velocity and channel height of 168. The main control parameter in the simulations is the Shields number that was varied between 0.03 and 0.60. The simulations were performed by means of a lattice Boltzmann scheme supplemented with an immersed boundary method to impose no-slip conditions at the particle surfaces. The results show the impact of the Shields number on the mobility of the particles at the top and above the bed. They also show a strong coupling between solids motion and the strength of the turbulent fluctuations in the liquid. Specifically, directly above the bed the particles significantly enhance turbulence at the lower end of the Shields number range investigated.