Static Frame Research Articles

Current Dynamically Predicting Control of PMSM Targeting the Current Vectors

This paper present a current predicting control method for PMSM (permanent magnet synchronous motor) to improve the tracking performance of stator current, which regards the current vector as the control target. Solving the model state equation in the static frame (α-β frame), the dynamic change of current vector will be gained as three independent terms. These change terms, which contain the prediction of current vector, are discretized and simplified by Taylor series expansion and used to get the voltage vector as the predictive control quantity. SVPWM will transform the control voltage to the switching signal of inverter, which is newly deduced for the current vector. Simulation and experiment results are given to testy and verify the performance of this method.

Backstepping control of speed sensorless permanent magnet synchronous motor based on slide model observer

This paper presents a backstepping control method for speed sensorless permanent magnet synchronous motor based on slide model observer. First, a comprehensive dynamical model of the permanent magnet synchronous motor (PMSM) in d-q frame and its space-state equation are established. The slide model control method is used to estimate the electromotive force of PMSM under static frame, while the position of rotor and its actual speed are estimated by using phase loop lock (PLL) method. Next, using Lyapunov stability theorem, the asymptotical stability condition of the slide model observer is presented. Furthermore, based on the backstepping control theory, the PMSM rotor speed and current tracking backstepping controllers are designed, because such controllers display excellent speed tracking and anti-disturbance performance. Finally, Matlab simulation results show that the slide model observer can not only estimate the rotor position and speed of the PMSM accurately, but also ensure the asymptotical stability of the system and effective adjustment of rotor speed and current.

Method for collecting thermocouple data via secured shell over a wireless local area network in real time.

This manuscript addresses the design, hardware details, construction, and programming of an apparatus allowing an experimenter to monitor and record high-temperature thermocouple measurements of dynamic systems in real time. The apparatus uses wireless network technology to bridge the gap between a dynamic (moving) sample frame and the static laboratory frame. Our design is a custom solution applied to samples that rotate through large angular displacements where hard-wired and typical slip-ring solutions are not practical because of noise considerations. The apparatus consists of a Raspberry PI mini-Linux computer, an Arduino micro-controller, an Ocean Controls thermocouple multiplexer shield, and k-type thermocouples.

Data-Driven Tight Frame for Multi-channel Images and Its Application to Joint Color-Depth Image Reconstruction

In image restoration, we usually assume that the underlying image has a good sparse approximation under a certain system. Wavelet tight frame system has been proven to be such an efficient system to sparsely approximate piecewise smooth images. Thus, it has been widely used in many practical image restoration problems. However, images from different scenarios are so diverse that no static wavelet tight frame system can sparsely approximate all of them well. To overcome this, recently, Cai et. al. (Appl Comput Harmon Anal 37:89–105, 2014) proposed a method that derives a data-driven tight frame adapted to the specific input image, leading to a better sparse approximation. The data-driven tight frame has been applied successfully to image denoising and CT image reconstruction. In this paper, we extend this data-driven tight frame construction method to multi-channel images. We construct a discrete tight frame system for each channel and assume their sparse coefficients have a joint sparsity. The multi-channel data-driven tight frame construction scheme is applied to joint color and depth image reconstruction. Experimental results show that the proposed approach has a better performance than state-of-the-art joint color and depth image reconstruction approaches.

Acceleration in de Sitter spacetimes

We propose a definition of uniform accelerated frames in de Sitter spacetimes applying the Nachtmann method of introducing coordinates using suitable point-dependent isometries. In order to recover the well-known Rindler approach in the flat limit, we require the transformation between the static frame and the accelerated one to depend continuously on acceleration, obtaining thus the natural generalization of the Rindler transformation to the de Sitter spacetimes of any dimensions.

Cosmic background radiation in the vicinity of a Schwarzschild black hole: No classic firewall

The Cosmic Blackbody Background Radiation pervades the entire Universe, and so falls into every astrophysical black hole. The blueshift of the infalling photons, measured by a static observer, is infinite at the event horizon. This raises a question as to whether a "firewall" of high energy density may form just outside the horizon, or whether the effect can be attributed exclusively to a singular behavior of the static observer's frame at the horizon. In principle, the presence of such firewall may alter the motion of the infalling matter, influence the black hole evolution, or even invalidate the {\it vacuum} Einstein field equation solution as a realistic approximation for black holes. In this paper we show by means of analytic calculations that all these effects indeed exist, but their magnitude is typically negligibly small, even though the matter stress tensor is divergent in the static frame at $r=2M$. That is not surprising because of the divergent relation of that frame to a freely falling frame as $r \rightarrow 2M$; however it represents a kind of classical analogue for the Black Hole Complementarity principle that has been proposed for quantum effects near a black hole. What is perhaps more surprising is the divergence of the radiation stress tensor for massive particles moving on circular geodesic orbits for values of $r$ approaching $r = 3M$. However such orbits will not occur for infalling matter in realistic accretion discs.

Strategy for dynamic 3D depth data matching towards robust action retrieval

3D depth data, especially dynamic 3D depth data, offer several advantages over traditional intensity videos for expressing objects׳ actions, such as being useful in low light levels, resolving the silhouette ambiguity of actions, and being color and texture invariant. With the wide popularity of somatosensory equipment (Kinect for example), more and more dynamic 3D depth data are shared on the Internet, which results in an urgent need to retrieve these data efficiently and effectively. In this paper, we propose a generalized strategy for dynamic 3D depth data matching and apply this strategy in action retrieval task. Firstly, an improved 3D shape context descriptor (3DSCD) is proposed to extract features of each static depth frame. Then we employ dynamic time warping (DTW) to measure the temporal similarity between two 3D dynamic depth sequences. Experimental results on our collected dataset consisting of 170 dynamic 3D depth video clips show that the proposed 3DSCD has a rich descriptive power on depth data and that the method using 3DSCD and DTW achieves high matching accuracy. Finally, to address the matching efficiency problem, we utilize the bag of word (BoW) model to quantize the 3DSCD of each static depth frame into visual word packages. So the original feature matching problem is simplified into a two-histogram matching problem. The results demonstrate the matching efficiency of our proposed method, while still maintaining high matching accuracy.

Study on Detection of Black Field and Static Frame in IPTV and Mobile TV’s Quality Supervision

With the digital and networked development in information industry, people's requirements for video playback quality step up, and people put forward higher requirements to the regulatory work. After timely detecting factors which effect the quality of video playback, such as: mosaic, no sound, black field, supervision departments take corresponding measures to adjust the broadcast program which is beneficial to improve the playback quality. Among them, this article made some analysis on the static frame and black field which are important parts of the program content detection, and tells us the causes and characteristics of them. Then we design the detection method for these two kinds of phenomena by controlling the static frame and black field threshold size .Finally, we use the MATLAB program to realize the detection of the static frame and black field.

Recovering metric properties of objects through spatiotemporal interpolation.

Spatiotemporal interpolation (STI) refers to perception of complete objects from fragmentary information across gaps in both space and time. It differs from static interpolation in that requirements for interpolation are not met in any static frame. It has been found that STI produced objective performance advantages in a shape discrimination paradigm for both illusory and occluded objects when contours met conditions of spatiotemporal relatability. Here we report psychophysical studies testing whether spatiotemporal interpolation allows recovery of metric properties of objects. Observers viewed virtual triangles specified only by sequential partial occlusions of background elements by their vertices (the STI condition) and made forced choice judgments of the object's size relative to a reference standard. We found that length could often be accurately recovered for conditions where fragments were relatable and formed illusory triangles. In the first control condition, three moving dots located at the vertices provided the same spatial and timing information as the virtual object in the STI condition but did not induce perception of interpolated contours or a coherent object. In the second control condition oriented line segments were added to the dots and mid-points between the dots in a way that did not induce perception of interpolated contours. Control stimuli did not lead to accurate size judgments. We conclude that spatiotemporal interpolation can produce representations, from fragmentary information, of metric properties in addition to shape.

Large Motor Rotor Machining with Static Pressure Center Frame Design

With the recent development of domestic hydropower industry, length, weight, size, material and structure of the rotor machining of large motors and generators manufactured workpiece special processing equipment and process methods have become increasingly demanding, aiming at market high precision, good quality, technical indicators have a good guarantee of the large rotor machining center with plenty of needs static frame, developed a long piece, big weight, material and structural special processing equipment. This equipment has proven high accuracy, good quality, technical indicators have a good guarantee to solve practical problems that exist in the above production. The large hydrostatic rotor machining center frame, not only to solve the large generators, turbine rotor shaft heavy machining of technical problems, but also to ensure the accuracy and stability of the product processing.

Researches on Data Privacy in Cloud Computing Based on Game Theory

Existing proposals for data privacy in cloud computing have typically been founded on encryption and are not well-balanced on dealing with the contradiction between data privacy and efficient queries. This paper discusses the data privacy in cloud computing based on the perspective of game theory. It built a complete information static game theory frame between a trusted data center and many un-trusted database service providers to avoid the coalition among un-trusted database service providers, and gave Nash equilibrium of mixed strategy. Some influence factors of Nash equilibrium are also analyzed.

The Detection Method of Black Field Failure and Static Frame Failure in Radio and Television Broadcast

Black field failure and static frame failure are two kinds of abnormal states in the process of radio and television broadcast. To explore an effective method to eliminate the two faults, so as to ensure the safety of radio and television broadcasting, has a very important practical significance. This paper introduces a method to detect black field failure and static frame failure which based on digital image processing techniques. During the detection,the image block processing is introduced, and the gray values of the inner frame images and the adjacent frame images need to be calculated and contrasted. The Matlab simulation analysis was carried on has proved its feasibility at last.

Researches on Data Correctness and Completeness in Cloud Computing Based on Game Theory

Ensuring data correctness and data completeness in cloud computing, in addition to security technologies, many other factors need also be considered, such as the behaviors of participants of cloud computing. This paper discusses the data correctness and completeness in cloud computing based on the perspective of game theory. It built a complete information static game theory frame between a trusted data center and an un-trusted database service provider, and gave the mixed strategy Nash equilibrium. It also proposed some countermeasures and suggestions to improve the data security in cloud computing.

Rotating black hole hair

A Kerr black hole sporting cosmic string hair is studied in the context of the abelian Higgs model vortex. It is shown that a such a system displays much richer phenomenology than its static Schwarzschild or Reissner--Nordstrom cousins, for example, the rotation generates a near horizon electric field. In the case of an extremal rotating black hole, two phases of the Higgs hair are possible: Large black holes exhibit standard hair, with the vortex piercing the event horizon. Small black holes on the other hand, exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon. This solution however is extremely sensitive to confirm numerically, and we conjecture that it is unstable due to a supperradiant mechanism similar to the Kerr-adS instability. Finally, we compute the gravitational back reaction of the vortex, which turns out to be far more nuanced than a simple conical deficit. While the string produces a conical effect, it is conical with respect to a local co-rotating frame, not with respect to the static frame at infinity. As a consequence, we find that the ergosphere is shifted, and geodesics around the black hole are perturbed.

Is Continuity a Static Frame of Reference?

Is Continuity a Static Frame of Reference?

Experimental study on the self-noise of a turbulent round jet investing a cambered aerofoil

This paper describes an experimental investigation of the interaction noise in a jet impacting isolated aerofoils. The authors conducted the study in a low-speed wind tunnel ending in an anechoic chamber, and focussed on the tip region of two types of isolated low speed axial fan cambered aerofoils. The authors set the Mach number, Reynolds number and blade incidence angles in a static frame of reference to reproduce a flow field condition kinematically similar to that in the rotating frame. They correlated far-field noise measurements with near-field pressure measurements which they took at different chord-wise positions in the blade’s tip region. The aim was to find, by means of a cross correlation technique, a causal relationship between the aerodynamic sources in the tip region and noise emissions in order to establish the role of aerofoil self-noise associated with turbulent structures which turbulent inflow and blade tip geometry interaction produced.

3D Radar Objects Tracking and Reflectivity Profiling

The ability to characterize feature objects from radar readings is often limited by simply looking at their still frame reflectivity, differential reflectivity and differential phase data. In many cases, time-series study of these objects' reflectivity profile is required to properly characterize features objects of interest. This paper introduces a novel technique to automatically track multiple 3D radar structures in C,S-band in real-time using Doppler radar and profile their characteristic reflectivity distribution in time series. The extraction of reflectivity profile from different radar cluster structures is done in three stages: 1. static frame (zone-linkage) clustering, 2. dynamic frame (evolution-linkage) clustering and 3. characterization of clusters through time series profile of reflectivity distribution. The two clustering schemes proposed here are applied on composite multi-layers CAPPI (Constant Altitude Plan Position Indicator) radar data which covers altitude range of 0.25 to 10 km and an area spanning over hundreds of thousands <TEX>$km^2$</TEX>. Discrete numerical simulations show the validity of the proposed technique and that fast and accurate profiling of time series reflectivity distribution for deformable 3D radar structures is achievable.

Static Frame Model Validation with Small Samples Solution Using Improved Kernel Density Estimation and Confidence Level Method

An improved method using kernel density estimation (KDE) and confidence level is presented for model validation with small samples. Decision making is a challenging problem because of input uncertainty and only small samples can be used due to the high costs of experimental measurements. However, model validation provides more confidence for decision makers when improving prediction accuracy at the same time. The confidence level method is introduced and the optimum sample variance is determined using a new method in kernel density estimation to increase the credibility of model validation. As a numerical example, the static frame model validation challenge problem presented by Sandia National Laboratories has been chosen. The optimum bandwidth is selected in kernel density estimation in order to build the probability model based on the calibration data. The model assessment is achieved using validation and accreditation experimental data respectively based on the probability model. Finally, the target structure prediction is performed using validated model, which are consistent with the results obtained by other researchers. The results demonstrate that the method using the improved confidence level and kernel density estimation is an effective approach to solve the model validation problem with small samples.

Dynamic evidential reasoning for change detection in remote sensing images

Theories of evidence have already been applied more or less successfully in the fusion of remote sensing images. These attempts were based on the classical evidential reasoning which works under the condition that all sources of evidence and their fusion results are related to the same invariable (static) frame of discernment. When working with multitemporal remote sensing images, some change occurrences are possible between two images obtained at a different period of time, and these changes need to be detected efficiently in particular applications. The classical evidential reasoning is adapted for working with an invariable frame of discernment over time, but it cannot efficiently detect nor represent the occurrence of change from heterogeneous remote sensing images when the frame is possibly changing over time. To overcome this limitation, dynamic evidential reasoning (DER) is proposed for the sequential fusion of multitemporal images. A new state-transition frame is defined in DER, and the change occurrences can be precisely represented by introducing a statetransition operator. Two kinds of dynamical combination rules working in the free model and in the constrained model are proposed in this new framework for dealing with the different cases. Moreover, the prior probability of state transitions is taken into account, and the link between DER and Dezert-Smarandache theory is presented. The belief functions used in DER are defined similarly to those defined in the Dempster-Shafer theory. As shown in the last part of this paper, DER is able to estimate efficiently the correct change detections as a postprocessing technique. Two applications are given to illustrate the interest of DER: The first example is based on a set of two SPOT images acquired before and after a flood, and the second example uses three QuickBird images acquired during an earthquake event.

Cell Geometry and Material Property Effects on Membrane and Flow Response

TO OPTIMIZE micro aerial vehicle (MAV) designs for size and speed regimes characteristic of small birds and insects, a growing subset of low-Reynolds-number research groups practice biomimetics to take advantage of nature-optimized designs proven effective within the MAV flight regime [1]. One common feature of many natural flyers is wing flexibility. Engineering models that mimic low-Reynolds-number fliers with fixed-wing flexibility have demonstrated improved aerodynamics compared with conventional rigid airfoils. This improvement is attributed to a combination of passive static and dynamic deformations of the flexible-membrane wings supported by semirigid, fixed-wing frames. Static deformation, of bothmembrane and frame, can advantageously affect airfoil camber and tip washout through inflation and alteration of aerodynamic and geometric twist [2–4]. Dynamic membrane deformations can improvemomentum transfer between the leeside free shear layer and recirculation region of models with rigid leading and trailing edges and a membrane attached in between, thereby, decreasing the extent of flow separation and corresponding wake size, as well as advantageously affecting the aerodynamic forces [5,6]. Similar vibrations also exist for membrane wings with an unattached trailing edge. Hubner and Hicks [7] showed aerodynamic efficiency improvement by scalloping the trailing edge and developed scaling trends with respect to cell geometry. Johnston et al. [8] demonstrated via high-speed imagery that membrane prestrain increased flutter onset velocity while reducing the magnitude of the postflutter limit cycle oscillations. A free trailing-edge wing structure typically includes a flat or cambered frame of moderate or low aspect ratio that is significantly less compliant than the attached membrane. The membrane is attached along the leading edge of the frame and along battens (or ribs) extending from the leading edge. In this Note, it is documented that the initial flutter onset frequency of zero-applied-pretension membranes originates from small-amplitude membrane vibrations at the natural frequency of the membrane. Although applied pretensioning will affect the frequency, cell geometry and material properties are shown to play an important role as well. Spectral data from the membrane and the leeside shear layer via simultaneously sampled hot-wire anemometry and laser vibrometry are presented and discussed in this Note.