Search

A scheduling method based on fuzzy feedback priority and variable sampling period for a networked control system with resource constraints is proposed in this paper. Firstly, each control loop weight is adjusted dynamically according to a control loop data transmission error through a quadratic square root mapping function. A different weight is given for each loop. A fuzzy feedback priority scheduling strategy is designed combined with dynamic weight, system output and system output error rate. The priority of each control loop is adjusted dynamically. Then, considering the current network status, the new network utilization is predicted through proportional control. A least-squares support vector machine (LSSVM) algorithm is used for controlled loop packet transmission time prediction. A variable sampling period for each control loop is determined by using a controlled loop dynamic weight, network utilization and data transmission time. Finally, a fuzzy feedback priority scheduler and variable sampling period scheduler are combined. The merits of the two schedulers are utilized to achieve the optimization goal. A simulation experiment is carried out using the True Time toolbox. Simulation results show that the scheduling method can make the network utilization rate converge to the desired value under resource constraints, improve the output response performance of the control loop, reduce the integral absolute error value of the control loop and decrease the data transmission time of the control loop. The networked control system performance is improved and the scheduling method of this paper is effective. [ABSTRACT FROM AUTHOR]

This paper studies a reliable control strategy for a bionic-ape brachiation robot with dual-arm hands, a four-link brachiate mechanism, which swings and grasps branches like a gibbon. Based on the analysis of the brachiation of gibbons and humans, the big damping nonholonomic constraints model is introduced. A control strategy which combines the energy pumping control with the big damping turn-back angle feedback control is proposed. The grasping motion was divided into several processes: the swing-up self-starting phase, the energy rising phase, the transition phase and the grasping phase. A self-starting controller is designed for swing-up motion from a downward stable position. In the energy rising phase, an energy pumping control law is deduced based on Lyapunov stability theory, and the singularity and convergence of the system are analyzed. The system energy is calculated periodically to determine if the robot gets enough energy for grasping, so that it could shift into the transition phase. A position–orientation control method is adopted to realize that the gripper grasps target bars in the desired position, orientation and speed. By means of ADAMS-MATLAB co-simulation, the bionic-ape robot achieves smooth swing-grasp motions under different heights and horizontal distances. The simulation results indicate that this method has advantages of universality and reliability in a grasping target bar. Therefore, the effectiveness of the proposed control strategy is validated. [ABSTRACT FROM AUTHOR]

Device-centric architecture is an important aspect for fifth generation (5G) networks. The current cellular systems are base station-centric where the base-station (BS) is responsible for resource allocation. The BS allocates resources to users based on their channel state information (CSI) and feedback. This resource allocation process increases load at the BS side resulting in more time consumption. This decreases the overall network throughput and increases delay in resource allocation. Therefore, in this article, a device-centric resource allocation scheme is proposed for D2D users. In this scheme, interested D2D pairs can allocate the resource to themselves using the following three steps. In first step, devices maintain their resource occupancy matrix by exchanging the neighbouring information. In second step, a resource block is selected based on resource allocation scenarios. In third steps, resource block is allocated based on the priority on the BS side. The proposed scheme is less dependent on the BS side, hence it reduces the load on BS side and it also reduces time consumption in resource allocation process. Additionally, the proposed scheme improves the overall network throughput. A comparison of the proposed scheme with the base-centric scheme shows that proposed scheme is up to 35% more effective in each experimental case. [ABSTRACT FROM AUTHOR]

An adaptive delay-tolerant distributed space-time coding (DSTC) scheme equipped with a feedback channel is proposed for two-hop cooperative multiple-input multiple-output (MIMO) networks. A maximum likelihood receiver and adjustable code matrices subject to a power constraint with a decode-and-forward cooperation strategy are considered with different DSTC antenna configurations. In the proposed delay-tolerant DSTC schemes, an adjustable code matrix is employed to transform the space-time coded matrices at the relay nodes. Stochastic gradient and least squares algorithms are also developed with reduced computational complexity. The proposed algorithms are then extended to a cooperative MIMO system using amplify-and-forward strategy and opportunistic relaying algorithms in order to develop a delay-tolerant coding scheme combined with optimal relay selection strategies. An upper bound on the pairwise error probability and a rank criterion analysis are derived which indicate the advantage of the proposed algorithms. Simulation results show that the proposed algorithms obtain significant performance gains and address the delay issue in cooperative MIMO systems as compared to existing DSTC schemes. [ABSTRACT FROM AUTHOR]

In this paper, Active Vibration Control (AVC) of a rectangular carbon fibre composite plate with free edges is presented. The plate is subjected to out-of-plane excitation by a modal vibration exciter and controlled by Macro Fibre Composite (MFC) transducers. Vibration measurements are performed by using a Laser Doppler Vibrometer (LDV) system. A fractional-order Positive Position Feedback (PPF) compensator is proposed, implemented and compared to the standard integer-order PPF. MFC actuator and sensor are positioned on the plate based on maximal modal strain criterion, so as to control the second natural mode of the plate. Both integer and fractional-order PPF allowed for the effective control of the second mode of vibration. However, the newly proposed fractional-order controller is found to be more efficient in achieving the same performance with less actuation voltage. Moreover, it shows promising performance in reducing spillover effect due to uncontrolled modes. [ABSTRACT FROM AUTHOR]

Sophisticated subthreshold passive radio frequency identification tag’s baseband processor (BBP) core design for ultralow-power Internet of Things end devices is presented in this paper. Custom logic cells and tailored logic architectures are applied to eliminate timing violations when the operating voltage is much lower than nominal level. For the consideration of limited availability of radio frequency power, power-aware scheme is applied to the key modules, including PIE decoding and command receiving. Furthermore, Galois linear feedback shift register and double-edge-triggered techniques help to improve clock efficiency and reduce the impact of frequency variation in data link portions. Importantly, a novel custom ratioed logic style is adopted in key modules to fundamentally speed up signals’ propagation at ultralow-voltage. The proposed BBP was fabricated in 90-nm CMOS as well as the regular design with the same function. It was also implemented in the tag chip’s fabrication. In measurement the proposed design indicates good robustness and is much more competent for subthreshold operation. It can operate below 0.3 V with power consumption below 130 nW. [ABSTRACT FROM PUBLISHER]

This paper presents novel solution of a fractional-order low-pass filter (FLPF). The proposed filter operates in the current mode and it is designed using third-order inverse follow-the-leader feedback topology and operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs), auxiliary multiple-output current follower (MO-CF) as simple active elements. The filter offers the beneficial ability of the electronic control of its order and also the pole frequency thanks to electronically controlled internal parameters of OTAs and ACAs. As an example, five particular values of fractional order of the FLPF were chosen and parameters of the filter were calculated. Similarly, also electronic control of the pole frequency of the filter was studied. The design correctness and proper function of the filter are supported by simulations with CMOS models and also by experimental laboratory measurements. Comparison of the simulation results of the proposed filter for two different approximations of the parameter aplha is also included. [ABSTRACT FROM AUTHOR]

The subset feedback vertex set problem generalizes the classical feedback vertex set problem and asks, for a given undirected graph G = ( V, E), a set S ⊆ V, and an integer k, whether there exists a set X of at most k vertices such that no cycle in G − X contains a vertex of S. It was independently shown by Cygan et al. (ICALP '11, SIDMA '13) and Kawarabayashi and Kobayashi (JCTB '12) that subset feedback vertex set is fixed-parameter tractable for parameter k. Cygan et al. asked whether the problem also admits a polynomial kernelization. We answer the question of Cygan et al. positively by giving a randomized polynomial kernelization for the equivalent version where S is a set of edges. In a first step we show that edge subset feedback vertex set has a randomized polynomial kernel parameterized by | S| + k with $\mathcal {O}(|S|^{2}k)$ vertices. For this we use the matroid-based tools of Kratsch and Wahlström (FOCS '12) that for example were used to obtain a polynomial kernel for s-multiway cut. Next we present a preprocessing that reduces the given instance ( G, S, k) to an equivalent instance ( G′, S′, k′) where the size of S′ is bounded by $\mathcal {O}(k^{4})$ . These two results lead to a randomized polynomial kernel for subset feedback vertex set with $\mathcal {O}(k^{9})$ vertices. [ABSTRACT FROM AUTHOR]

Since 2011, the Kraemer Family Library at the University of Colorado Colorado Springs (UCCS) has offered Scrabble Scramble, an in-person, student-centered library orientation game, to incoming first-year students. This article describes our journey of developing, assessing, and refining Scrabble Scramble, which focuses on introducing first-year students to the basic services and resources of an academic library. Through analysis of student and library staff feedback survey results, this article reflects on the value of offering a student-centered, impactful, and personal orientation in an environment of rising student enrollment, steady staff numbers, and a trend to move orientation activities online. [ABSTRACT FROM AUTHOR]

Adaptive feedback cancellation (AFC) techniques are common in modern hearing aid devices (HADs) since these techniques have been successful in increasing the stable gain. Accordingly, there has been a significant effort to improve AFC technology, especially for open-fitting and in-ear HADs, for which howling is more prevalent due to the large acoustic coupling between the loudspeaker and the microphone. In this paper, the authors propose a hybrid AFC (H-AFC) scheme that is able to shorten the time it takes to recover from howling. The proposed H-AFC scheme consists of a switched combination adaptive filter, which is controlled by a soft-clipping-based stability detector to select either the standard normalized least mean squares (NLMS) algorithm or the prediction-error-method (PEM) NLMS algorithm to update the adaptive filter. The standard NLMS algorithm is used to obtain fast convergence, while the PEM-NLMS algorithm is used to provide a low bias solution. This stability-controlled adaptation is hence the means to improve performance in terms of both convergence rate as well as misalignment, while only slightly increasing computational complexity. The proposed H-AFC scheme has been evaluated for both speech and music signals, resulting in a significantly improved convergence and re-convergence rate, i.e., a shorter howling period, as well as a lower average misalignment and a larger added stable gain compared to using either the NLMS or the PEM-NLMS algorithm alone. An objective evaluation using the perceptual evaluation of speech quality and the perceptual evaluation of audio quality measures shows that the proposed H-AFC scheme provides very high-quality speech and music signals. This has also been verified through a subjective listening experiment with N = 15 normal-hearing subjects using a multi-stimulus test with hidden reference and anchor, showing that the proposed H-AFC scheme results in a better perceptual quality than the state-of-the-art PEM-NLMS algorithm. [ABSTRACT FROM AUTHOR]

SUMMARY A single or multiple kinds of internal or external environmental variations of the system often cause the property variation of any system under control, and the readjustment of controller parameters is required. To maintain high performance of controlling and minimize the total cost for readjustments of the controller parameters, determination of the appropriate timing for readjustment of the controller parameters is important. This paper proposes new procedure to determine the appropriate timing for the readjustments based on the time-series data using the recurrent neural networks (RNNs). A well-coordinated RNN with proper structure has high performance on the time-series data forecasting with the assistance of its internal signal feedback structure. This paper conducts some numerical experiments to verify the availability of the proposed method to some systems. The experimental result indicates that the proposed method has higher performance than other existing method with the same aim. [ABSTRACT FROM AUTHOR]

New output feedback-linearisation theory is presented for the treatment of nonlinear vibration problems by a receptance-based approach. An important aspect is a new formulation for investigating the stability of the zero dynamics. The overall methodology possesses the usual benefits of the receptance method, namely that the system matrices (with associated assumptions and approximations) do not have to be known. In addition, it has the distinction of not requiring the form and parameter values of the nonlinearity when the input and output degrees of freedom are away from the nonlinearity itself. This represents a valuable advance over the conventional time-domain feedback linearisation approach. [ABSTRACT FROM AUTHOR]

The performance of modular multilevel converters (MMCs) in medium-voltage applications, where the number of required submodules is not high, can be improved utilizing low switching frequency modulations such as (2N+1) selective harmonic elimination-pulse width modulation (SHE-PWM), which provides tight control of lower order harmonics and low switching losses. This paper proposes a calculation method, which is based on a novel formulation, to solve the SHE-PWM problem. In particular, MMCs with (2N+1) phase output voltage levels are considered, obtaining a (2N+1) SHE-PWM waveform. This method utilizes a unique system of equations that is valid for any possible waveform. Therefore, it is able to calculate simultaneously, without predefined waveforms, both the switching patterns and the associated firing angles that solve the (2N+1) SHE-PWM problem. Consequently, the search process is simplified and optimized. Furthermore, this paper also proposes a circulating current control technique, which can be applied along with (2N+1) SHE-PWM without disturbing the phase output voltage. Simulation results and experimental tests obtained with a single-phase laboratory prototype prove the validity of the novel (2N+1) SHE-PWM implementation method and the proposed circulating current control technique. [ABSTRACT FROM PUBLISHER]

This paper presents a simple method to analyze the behavior of feedback loops that contain a naturally-sampled single-edge pulse-width modulator. A small-signal model is derived by means of simple geometric arguments. It is shown how this small-signal model can be used to analyze the stability of the continuous-time pulse-width modulated feedback loop by using standard $z$-domain techniques. The strategy relies on familiar concepts like transfer functions and small-signal gains and does not require any in-depth knowledge of nonlinear systems. A simple design process, where the continuous-time compensator is designed directly in the $z$-domain, is developed and detailed design equations are derived for a PI current regulator. It is shown how the proposed strategy can accurately predict instability that cannot be explained by means of the well-known average model of the pulse-width modulator. The theoretical analysis is confirmed by means of detailed time-domain simulations. The mechanisms that lead to instability are discussed and an equation for the critical loop gain is derived. [ABSTRACT FROM PUBLISHER]

A control strategy for LCL grid-connected voltage source inverters is proposed. Using the injected grid current measurement exclusively, the proposal allows the use of the proportional plus resonant regulator optimum design, regardless of the filter resonance frequency. Simulation and experimental results that demonstrate the validity and effectiveness of the proposal for different LCL filter resonance frequency values are presented. Also its superiority compared with a control method recently proposed in the literature is shown. [ABSTRACT FROM PUBLISHER]

Modular multilevel converters (MMCs) are multi-input multi-output (MIMO) nonlinear systems. The control systems for MMCs are required to simultaneously achieve multiple control objectives, e.g., output current regulation, submodule capacitor voltage control, and circulating ripple currents suppression. Existing cascaded control strategies for MMCs achieve those control objectives with relatively complex controllers, and the controller parameter design is normally difficult for such nonlinear systems with highly coupled states. In view of this, a feedback linearization-based current control strategy is proposed for an MMC system in this paper. The nonlinear state function model of the MMC is presented and transformed to a linearized and decoupled form with the help of the input–output feedback linearization technique. Based on the linearized system, simple linear controllers are employed to regulate the output and inner differential currents of the MMC, which significantly reduces the difficulty in controller design. The stability of the proposed control strategy is analyzed. The experimental verification results show that, compared to the conventional cascaded control strategies for MMCs, the proposed feedback linearization control strategy is able to achieve improved steady-state and dynamic performances. The robustness of the proposed control strategy against parametric uncertainties is experimentally investigated. [ABSTRACT FROM PUBLISHER]

In this paper, we propose an imperfect quantized feedback-based diagonal precoding scheme for generalized orthogonal space-time block codes in an $N \times 1$ multiple-input single-output (MISO) wireless communication system employing $M$ -QAM constellation. It is well known that a feedback-based precoding scheme aids channel adaptive signaling in wireless communication system and capitulates large improvements in almost all performance metrics. However, a practical feedback link is susceptible to error due to wireless channel fading and leads to wrong precoder selection. Therefore, a signal-to-noise ratio (SNR) adaptive error-tolerant weighting scheme is introduced which provides significant gain in comparison with another proposed arbitrarily fixed SNR error-tolerant weighting scheme. At first, a tight approximate closed-form expression of average symbol-error-rate (SER) and an exact analytical expression of outage probability are derived under imperfect feedback information with the help of order statistics. By minimizing the derived average SER, optimized transmit weights for the diagonal precoding matrix (based on feedback bits) are obtained. Later, a closed-form expression of the ergodic capacity with erroneous feedback bits for arbitrary MISO system is also provided by using the moment generating function approach. Further, numerical results show that the considered error-tolerant schemes outperform the uniform power allocation scheme in term of all the investigated performance metrics. [ABSTRACT FROM AUTHOR]

The primary resonance of van der Pol oscillator under fractional-order delayed negative feedback and forced excitation is studied. Firstly, the approximate analytical solution is obtained based on the averaging method, and it could be found that the fractional-order delayed feedback has not only the property of delayed velocity feedback but also that of delayed displacement feedback. Moreover, the amplitude-frequency equation for the steady-state solution is established, and its stability conditions are also obtained. Then, the results of the approximate analytical solution and numerical integration are compared and analyzed. The agreement between the two methods is very high, so that the correctness and accuracy of the approximate analytical solution are verified. Finally, the effects of all the parameters in the fractional-order delayed feedback on the amplitude-frequency curves are analyzed. It could be concluded that fractional-order delayed feedback has important influences on the dynamical behavior of van der Pol oscillator, which is very significant to the optimization and control of a similar system. [ABSTRACT FROM AUTHOR]

The increasing availability of implicit feedback datasets has raised the interest in developing effective collaborative filtering techniques able to deal asymmetrically with unambiguous positive feedback and ambiguous negative feedback. In this paper, we propose a principled kernel-based collaborative filtering method for top-N item recommendation with implicit feedback. We present an efficient implementation using the linear kernel, and we show how to generalize it to kernels of the dot product family preserving the efficiency. We also investigate on the elements which influence the sparsity of a standard cosine kernel. This analysis shows that the sparsity of the kernel strongly depends on the properties of the dataset, in particular on the long tail distribution. We compare our method with state-of-the-art algorithms achieving good results both in terms of efficiency and effectiveness. [ABSTRACT FROM AUTHOR]

Carbon emissions of power industry in China have accounted for more than half of the total emissions. How to decrease them is important for realizing carbon emission reduction. This paper proposes a carbon market feedback mechanism to power market, comprehensively considering the influence of generation structure, carbon intension, and technological progress on carbon emission reduction in power industry, and builds a potential model based on dynamic system. Operation system results show that the increasing trend of carbon emission can be controlled effectively but always with a lag. At the same time, sensitivity analysis results show that carbon emission reduction can be better realized by adjusting power structure and improving technological level; the former can reduce 32% and the latter can reduce 60% at most. [ABSTRACT FROM AUTHOR]

A decision feedback circuit with integrated offset compensation is presented in this paper. The circuit is built around the sense amplifier comparator. The loop latency is reduced by closing the feedback loop around the first stage. The feedback loop is implemented using a switched capacitor network that picks from one of pre-computed voltages to be fed back. The comparator's offset that is to be compensated for, is added in the same path. Hence, an extra offset correction input is not required. The circuit is used as a receiver for a 10 mm low swing interconnect implemented in UMC 130 nm CMOS technology. The circuit is tested at a frequency of 1 GHz and it consumes 145 μ A from a 1.2 V supply at this frequency. [ABSTRACT FROM AUTHOR]

Secure communication with noisy feedback is studied in this correspondence. Unlike the majority of previous research efforts where the eavesdropper's channel state information (CSI)—either instantaneous or statistical CSI, is known by the legitimate users, a joint feedback and artificial noise scheme without any eavesdropper's CSI is proposed. The proposed scheme lets the source and the legitimate destination alternatively transmit private messages and degrade the eavesdropper's channel quality in all transmission phases. An insightful discovery is that if the transmit power is lager than a certain threshold, a positive secrecy capacity can be achieved, which overcomes the problem that the secrecy cannot be achieved when the legitimate user's CSI is worse than the eavesdropper's. The secrecy capacity maximization problem is investigated by adaptive power allocation for the private signals and the artificial noise where a near optimal solution of the power of artificial noise is obtained under the high SNR situation. Finally, the numerical results verify the theoretical analysis and illustrate the secrecy performance of the proposed scheme. [ABSTRACT FROM AUTHOR]

In design of Continuous-time Delta-Sigma modulators, the feedback DAC (Digital-to-Analog Converter) is typically implemented with a switched current circuit. It is desired that these DAC current circuits provide constant current across clock cycles for each modulator output level. However, when Delta-Sigma modulators are implemented with Gm-C integrators, the DAC feedback current circuits are directly connected to the integrator outputs that may have high-swing voltages and this results in varying DAC feedback current. In this paper, we analyze the effect of feedback current variation caused by high-swing integrator output voltages in Delta-Sigma modulators built with Gm-C integrators. It is shown that feedback current variation may significantly degrade the performance of Delta-Sigma modulators mainly due to the non-linearity of current variation dependence on the integrator output voltage, while mismatch of current variation has minor effect. [ABSTRACT FROM AUTHOR]

In this paper, we propose the analytical approach for amplify-and-forward (AF) opportunistic relaying schemes (ORS). When operation of AF-ORS consists of relay selection and data transmission phases based on pilot symbol assisted-channel estimation (PSA-CE) methods over quasi-static Rayleigh fading channels, we show that the relay selection phase can be implemented by pilots symbols transmission for source-relay and relay-destination. Moreover, the feedback method for the selected relay index is proposed to have a simple fashion. Then, we investigate the effects of both a channel estimation error and an estimated noise variance, which are obtained by PSA-CE methods, on the received signal-to-noise ratio (SNR). The average SNR loss is also derived in terms with the number of pilots in PSA-CE methods. Moreover, the average symbol error rate, the outage probability, and the normalized channel capacity of the ORS are derived in approximated closed-form expressions for an arbitrary link SNR when the channel state information in the source-relay-destination link is estimated based on transmitted pilots symbols. As the number of pilot symbols, the derived analytical approach is verified, and by comparing it with simulation results, the accuracy is demonstrated. In addition, it is verified that the effect of the feedback error can be neglected for PAS-CE methods over quasi-static fading channels. [ABSTRACT FROM AUTHOR]

In Very-Large-Scale Integration (VLSI), the main challenges for the researchers are to reduce the power dissipation by the devices. In this paper, the authors have proposed a modified version of the Linear Feedback Shift Register to meet the specific output. The power consumption can be reduced by deactivating the clock signal from the flip flop to design test pattern generator during testing power. The LFSR pseudo-random test pattern generator is used in the testing of the ASIC chips, which is used to generate the random sequences of the desired pattern generator. This paper will help in the reduction of additional test inputs used for the ASIC. The test pattern is generated in such a way that the component requirements can be reduced. [ABSTRACT FROM AUTHOR]

A Smart Grid combines the use of traditional technology with innovative digital solutions, making the management of the electricity grid more flexible. It allows for monitoring, analysis, control and communication within the supply chain to improve efficiency, reduce the energy consumption and cost, and maximize the transparency and reliability of the energy supply chain. The optimization of energy consumption in Smart Grids is possible by using an innovative system based on Non Intrusive Appliance Load Monitoring (NIALM) algorithms, in which individual appliance power consumption information is disaggregated from single-point measurements, that provide a feedback in such a way to make energy more visible and more amenable to understanding and control. We contribute with an approach for monitoring consumption of electric power in households based on both a NILM algorithm, that uses a simple load signatures, and a web interactive systems that allows an active role played by users. [ABSTRACT FROM AUTHOR]

The response of a commercial-grade, single-mode vertical-cavity surface-emitting laser to very strong optical feedback is investigated. With increasing feedback magnitude, the lasing spectrum broadens dramatically, eventually resulting in coherence collapse, and the lasing peak shifts to longer wavelengths. These effects became less severe with the onset of higher-order modes. A theoretical model is provided to explain the redshifting of the lasing spectrum with feedback. [ABSTRACT FROM AUTHOR]

There have been few studies examining the variation that exists within modes of feedback: for example, comparing how electronic text feedback created using Google Docs differs from electronic text feedback created using Microsoft Word or how audiovisual feedback created using TechSmith Capture differs from audiovisual feedback created using Screencast-O-Matic. However, the programs that instructors use to create feedback have different affordances, meaning that even within a single mode, the feedback students receive on their writing can vary significantly. To better understand the variation that exists within a single mode, this study investigates how affordances of Canvas Speedgrader, Google Docs, and Turnitin GradeMark impacted electronic text feedback.Based on analysis of 131 feedback files created using the 3 programs, in conjunction with 5 student surveys, and 2 instructor interviews, the study provides insights into how instructor written commentary (location, form, type, focus, and mitigation) varied by program and how participants perceived of feedback provided through the 3 programs. The study...s primary finding is that the affordances of the programs used to create electronic text feedbackresulted in significant differences ininstructorcommentary and instructor and student perceptions of feedback. • Features of electronic text feedback differed depending on the program used to create it. • Program used made a difference to comment location, type, focus, and form. • Participants perceived of feedback differently depending on the program used. • Affordances of the programs associated with convenience were especially valued. [ABSTRACT FROM AUTHOR]

This work proposes a non-orthogonal selection cooperation scheme with interference for multi-source and single destination cooperative networks. In our model, the source nodes can cooperate for one another, i.e., each source node plays the dual role of a source and a relay, thus there is no need for relays. In addition, the source nodes can be continuously transmitted and without dedicated timeslots for cooperative transmissions, which can save system resources and improve spectral efficiency. However, by this way, it will introduce interference with the non-orthogonal transmission mechanism. To overcome this problem, we use general reception scheme in source nodes and successive interference cancellation technology in the destination node, which can reduce the effect of interference effectively. For interference-limited networks, we also derive the theoretical upper bound and lower bound of outage probability of our method. Through the outage probability analysis and comparison, the results show that the spectral efficiency is improved while the system still keeps acceptable transmission reliability. [ABSTRACT FROM AUTHOR]

Recent development of internet and its applications has become the source for research in service recommendation. Among them, point of interest (POI) recommendation based on user behaviour has enticed a decent attention. Along with quality of recommendations, the utilization of user feedback has grown to be a key part in the POI recommendations. While implementing similarity-based methods in conventional recommender systems, it faces various issues such as trustworthiness, sparsity and cold-start. The commonness and popularity of social network facilitate people to interact with different users and generate massive data such as user relationships, ratings and interactions. Thus, integration of trust relationship of user in location based social network along with their feedback for POI recommendation is the motivation of this work. In this article, we present a POI recommendation method based on trust enhancement in social networks known as social pertinent trust walker (SPTW). Initially, the level of trust between users in social networks is calculated through matrix factorization technique. Then, SPTW with high probability location category algorithm helps to generate POIs as list of recommendations. Experiments on real-world datasets are conducted to evaluate proposed algorithm for accuracy. Results reveal the effectiveness of approach and quality of recommendations is better, when compared to existing algorithms. [ABSTRACT FROM AUTHOR]

Mobile platforms have called for attention from HCI practitioners, and, ever since 2007, touchscreens have completely changed mobile user interface and interaction design. Some notable differences between mobile devices and desktops include the lack of tactile feedback, ubiquity, limited screen size, small virtual keys, and high demand of visual attention. These differences have caused unprecedented challenges to users. Most of the mobile user interface designs are based on desktop paradigm, but the desktop designs do not fully fit the mobile context. Although mobile devices are becoming an indispensable part of daily lives, true standards for mobile UI design patterns do not exist. This article provides a systematic literature review of the existing studies on mobile UI design patterns. The first objective is to give an overview of recent studies on the mobile designs. The second objective is to provide an analysis on what topics or areas have insufficient information and what factors are concentrated upon. This article will benefit the HCI community in seeing an overview of present works, to shape the future research directions. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative MAC protocol called I-MAC. Protocol for wireless sensor networks, which combines the advantages of collision tolerance and collision cancellation. The protocol increases the number of antenna in wireless sensor nodes. The purpose is to monitor the occurrence of packet collisions by increasing the number of antenna in real time. The built-in identity structure is used in the frame structure in order to help the sending node to identify the location of the receiving node after a data packet collision is detected. Packets can be recovered from where the conflict occurred. In this way, we can monitor the conflict for a fixed period of time. It can improve the channel utilisation through changing the transmission probability of collision nodes and solve the problem of hidden terminal through collision feedback mechanism. We have evaluated our protocol. Our results show that the throughput of I-MAC is 5 percentage points higher than that of carrier sense multiple access/collision notification. The network utilisation of I-MAC is more than 92%. [ABSTRACT FROM PUBLISHER]

This article proposes a novel digital predistortion (DPD) implementation method for RF power amplifiers. The new approach adopts only one 1-bit comparator in the feedback path to observe the in-phase (I) or the quadrature (Q) component of the error signal between the input and the output signals. To this end, the theoretical derivation of the in-phase observation based on direct learning architecture (DLA) DPD is first given in this article, by combining the existing 1-bit method and the low-cost in-phase observation. To facilitate the delay estimation and alignment, a modified iterative frequency-domain delay estimation is presented, which only acquires either I or Q components of the output signal to achieve satisfied delay estimation. Experimental results show that the proposed DPD method decreased the normalized mean square error (NMSE) and the adjacent channel power ratio (ACPR) to less than −42 and −51 dB, respectively, which indicates that the proposed DPD system can achieve comparable performance as the existing DPD identification techniques with lower implementation complexity. [ABSTRACT FROM AUTHOR]

This paper considers the design of simultaneous static output feedback controllers for a finite collection of time-delay linear systems. By solving a minimization problem, we try to find an output feedback low-gain controller such that all resultant closed-loop time-delay systems are internally stable and satisfy a prespecified H∞-norm requirement. Based on the barrier method, necessary conditions for local optimum of the minimization problem are derived. An example is given for illustration. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper addresses trade-offs in adaptive feedback cancellation (AFC) for hearing aids. Aggressive AFC for improved added stable gain (ASG) reduces speech quality. In this paper, the hearing-aid speech quality index (HASQI) is used to investigate AFC performance before the system becomes unstable. It is demonstrated that for a desired speech quality, multiple AFC algorithms can be evaluated for their ASG and computational efficiency. An example is presented with HASQI=0.8, baseline AFC, and two advanced approaches. For the advanced AFCs, ASG gains of 4 and 7 dB were obtained at additional computational complexity of 8% and 11%, respectively. [ABSTRACT FROM AUTHOR]

Optical feedback originating from the interfaces of the periodically poled domains of a nonlinear crystal is usually blocked by a bulky optical isolator to avoid an influence on the pump source. Here, a nonlinear bulk crystal with a slanted design of the periodic poling is used to suppress the optical feedback toward the laser source. This crystal is compared with a conventionally poled crystal, in which the incident radiation propagates perpendicular to the domains. Both crystals are made of magnesium oxide doped congruent lithium niobate (PPMgO:CLN). A distributed Bragg reflector tapered diode lasers with a maximum optical power of 7.0 W at a wavelength of 1122 nm and each nonlinear crystal are employed in a single-pass setup. In comparison with the conventional crystal, the optical feedback of the crystal with slanted domains is reduced by 13.4 dB enabling a stable narrow-band operation of the pump laser source without an optical isolator. The impact of the optical feedback on the diode laser with respect to the optical output power and the spectral behavior is investigated. For the crystal with slanted domains, a frequency doubled output power up to 0.39 W at 561 nm is generated without reaching the coherence collapse regime, as observed in case of the conventional crystal. These results are promising for miniaturization of the setup without a need for a bulky optical isolator. [ABSTRACT FROM PUBLISHER]