Mental Workload (MWL) is a construct widely used in HCI to assess the cognitive demand users must exert to perform a task. Research in human factors, however, has suggested several issues regarding its definitions, scales, and applications. This paper, first, introduces debates surrounding the MWL concept and its most popular measure, the NASA-TLX. We present a systematic review of CHI papers involving MWL and highlight severe issues in its application. Finally, through a validation experiment, we assess the convergent validity and sensitivity of two MWL instruments—NASA-TLX and MRQ. Our findings reveal disagreements in the definitions of MWL and severe drawbacks in NASA-TLX and its applications. Our validation study also presents evidence for a lack of convergent validity and sensitivity of MWL subjective scales in HCI tasks. Our findings recommend caution when employing NASA-TLX in user studies and highlight the need for an MWL definition that is agreed upon within the HCI community.

A Multisource Inverter (MSI) comprises several DC sources in the input that can be combined together with varying voltage levels to operate at different loads to reduce the battery size of electric vehicles. Different multisource inverter configurations have been presented recently in the literature. These structures use two DC sources to operate at different demand loads by using a low battery size. The weakness of these multisource inverters is that they use a high number of power switches. In addition, these structures cannot connect two DC used sources together in series to operate under a heavy load, which increases the battery's size, increases high power losses, and reduces efficiency due to a high number of switches. This paper proposes a new topology for multisource inverters that reduces the power electronics switches and the battery size due to generating four combinations between the two used DC sources in the proposed technique. The proposed multisource topology is controlled by the model predictive due to its popular advantages. The performance of the proposal is verified through simulation results in Matlab. The results show that the MPC is a good alternative for such applications due to its simplicity, high performance, and low harmonic content.

The transformer-based inverters in PV systems increase the weight, size, and cost of the inverter while reducing efficiency. This research presents a new PV inverter topology to increase efficiency using a reduction of dc-link. The proposed multilevel inverter is comprised of six power switches, one discrete diode, and three capacitors to produce five voltage levels. The proposed inverter is connected to a PV panel at input and a local grid at output to inject a sinusoidal current waveform into the grid. To control the grid current, a finite set model predictive control is needed to evaluate the proposed inverter. A comparison study is carried out between the proposal and other five-level inverters to verify the strengths and weaknesses of the proposed multilevel inverter. Finally, to demonstrate the performance of the proposed multilevel inverter, the simulation results are presented in the MATLAB/Simulink environment.

Electrodermal activity data is widely used in HCI to capture rich and unbiased signals. Results from related fields, however, have suggested several methodological issues that can arise when practices do not follow established standards. In this paper, we present a systematic methodological review of CHI papers involving the use of EDA data according to best practices from the field of psychophysiology, where standards are well-established and mature. We found severe issues in our sample at all stages of the research process. To ensure the validity of future research, we highlight pitfalls and offer directions for how to improve community standards.

In this paper, a new half-bridge inverter based on transformer-Z-network is proposed. The proposed Z-source inverter is suitable for applications which require dc/ac conversion with high voltage gain. The advantages of the proposed half-bridge inverter in comparison with classic half-bridge inverter are generating zero voltage level in the output and high boost factor at low value of the shoot-through duty cycle. In this paper, different operating modes of the proposed inverter are introduced and corresponding equations are derived. Logical diagram and waveforms of the switching pattern are presented. Moreover, design considerations for magnetizing inductors and capacitors are provided. Comparison of boost factor between the proposed and conventional inverters shows capability of the proposed inverter of generating high boost factor. To validate correct operation of the proposed half-bridge inverter, simulation results using PSCAD/EMTDC software and experimental results are provided.

Automatically detecting attentional states is a prerequisite for designing interventions to manage attention - knowledge workers' most critical resource. As a first step towards this goal, it is necessary to understand how different attentional states are made discernible through visible cues in knowledge workers. In this paper, we demonstrate the important facial cues to detect attentional states by evaluating a data set of 15 participants that we tracked over a whole workday, which included their challenge and engagement levels. Our evaluation shows that gaze, pitch, and lips part action units are indicators of engaged work; while pitch, gaze movements, gaze angle, and upper-lid raiser action units are indicators of challenging work. These findings reveal a significant relationship between facial cues and both engagement and challenge levels experienced by our tracked participants. Our work contributes to the design of future studies to detect attentional states based on facial cues.

Reactive power planning problem is the key to secure and economic operation of power systems. Optimal management of existing reactive sources leads to loss minimization and economic performance of the system. Because of the nonlinear inter-relation between the physical parameters of the electric grid, this problem is a highly nonlinear and nonconvex constrained optimization problem. The application of semidefinite programming (SDP) to power system problems has recently gained considerable research attention. A recent SDP formulation uses a convex relaxation to the nonconvex optimal power flow problem under some technical conditions. This paper proposes a novel equivalent convex optimization formulation for the optimal reactive power dispatch (ORPD) problem and presents a new framework for finding the global optimum. Numerical results for the IEEE 30-bus and 118-bus test systems show that the proposed scheme obtains the optimum operation point and outperforms various state-of-the-art methods significantly.

In this article, a new soft switching isolated push-pull dc-dc converter using a three-winding transformer is proposed. The proposed hybrid resonant and pulse width modulated converter employs a conventional push-pull structure in the primary side, a voltage doubler in the secondary side, and a bidirectional switch besides the transformer, altogether help offering a high efficiency over a wide range of input and output voltage signals with an unsophisticated fixed-frequency control mechanism. The primary-side switches are commutated under zero voltage switching with low switching current and the secondary-side diodes are commutated under zero current switching. In this article, we first present an in-depth analysis of various operation modes and design constraints. Our analysis is further complemented with a comprehensive reliability evaluation of the proposed converter under various short circuit and open circuit fault scenarios. Different from the previous research, the derated operating states of the proposed converter are detailed and characterized in the reliability evaluations. A comparison study is then provided to evaluate the performance of the proposed converter against other similar converters from the operation, components count, efficiency, and reliability perspectives. Finally, the theoretical analyses are verified via tests and experiments performed on a 280 W/34.7 kHz prototype.

This paper proposes a new multilevel module for the cascaded multilevel inverter configurations. The proposed basic module consists of n number of the conventional two-level inverter connected by series-connection (called a multilevel module MLM) and one power switch with one power diode and are parallel together that generate positive and negative voltage levels. The proposed cascaded multilevel inverter analyzed in both states of symmetric and asymmetric. In order to generate all voltage levels (even and odd) at the output, three new algorithms to determine the magnitude of dc voltage sources proposed. The main advantages of proposed topology are increasing the number of voltage levels at the output with a lower number of power semiconductor switches, driver circuits, and dc voltage sources. Therefore, the proposed topology needs to smaller installation area and lower weight and reduces the total cost of the inverter. Experimental results from a laboratory-scale prototype presented to verify the performance of the proposed multilevel inverter.

This paper proposes an efficient analytical harmonic elimination procedure valid for cascaded multilevel converters having s dc sources and a number of level l = 2s+1 with s = 2nn = 1,2,3, .... This procedure eliminates n+1 harmonics and their respective multiple; this implies a very low Total Harmonic Distortion. A 9-level inverter prototype is built and experimental results are obtained. The accuracy of the presented procedure is proved by the agreement between computed and experimental results.or, is observed.

In this paper, a dual parallel connected brushless direct current (BLDC) motors drive system fed by a single inverter is presented and the control method for stable operation in electric vehicles (EVs) application is proposed. To obtain the stability of such a system, both motors should always be respect the synchronism even if they have different load torque. The proposed control method is based on master-slave (MS) strategy. The motor with the highest load or lowest rotor position is selected as the master one and is directly controlled. Thus, rotor positions are compared to find the master motor. Simulation results are illustrated in different operation conditions to verify the performance of the drive system.

In this paper, a new quasi-Y source buck-boost dc-dc converter is proposed. The proposed converter uses a quasi-Y impedance network, which consists of a three-winding transformer, or three tightly coupled inductors. The proposed converter inherits all the advantages of the original quasi-Y source dc-dc converter such as continuous input current, lack of saturation in the magnetic core of the transformer, small duty cycle and high gain. The advantage of the proposed converter is adding the buck-boost ability to the conventional structure, which is crucial for some applications such as wind turbines and battery charging systems, which demand a buck-boost converter in their structure. The mathematical analyses are provided in order to investigate the operation principles of the converter. Also, in order to verify the proper functioning of the proposed converter, simulations are done in PSCAD/EMTDC and the results and waveforms are provided in the paper.

In this paper, a new quasi Z-source inverter based on new capacitor basic units (CAQZSI) is proposed. It is possible to develop the proposed topology by using n numbers of the basic units that is one of the main advantages of the proposed CAQZSI. The boost factor equation, voltage and current equations of the capacitors, diodes and inductors are obtained for the proposed topology and developed CAQZSI. High value of the boost factor based on the same value of shoot-through (ST) duty cycle without increasing the number of used active elements, same values of the capacitors voltage stress, diodes voltage stress and inductors current are the other advantages of the proposed CAQZSI in comparison with the conventional Z-source inverter (ZSI). Finally, the accuracy performance of the proposed topology is reconfirmed by using the simulation results in PSCAD/EMTDC software.

In this paper, a new continuouse current quasi Z-source inverter (CCQZSI) based on capacitor basic unit is proposed. By using n numbers of the basic units, the developed CCQZSI is proposed. High value of the boost factor is the main advantages of the proposed CCQZSI in comparison with the conventional Z-source inverter. This feature is obtained by considering same value of shoot-through (ST) duty cycle. In the proposed topology, the voltage stress equations of all used capacitors and diodes are calculated. Moreover, the current equations of the output dc link and inductors are obtained. According to the inductors current equations, input dc current source is equal to the current value of all inductors. In addition, by increasing the numbers of used basic units, the value of different inductors are as same as to each other and dc link current is decreased. Finally, the accuracy performance of the proposed topology is reconfirmed by using the simulation resluts in PSCAD/EMTDC software.

This paper proposes a comprehensive analysis of switched boost inverter's (SBI) voltage and current equations, using specific switching method in continuous current mode (CCM) operation. The presented switching method makes SBI proper to be used in galvanic and electrochemical applications. The boundary amount of inductor between the two CCM and discontinuous current mode (DCM) operations is calculated and also the operative parameters are determined. In addition, the diodes' and switches' voltage and current stresses, the inductor's current ripple and the capacitor's voltage ripple equations are represented which are needful to design the components. Moreover, the switching control circuit is proposed. Finally, the PSCAD/EMTDC software program results are given to show the theoretical analysis validation.

This study suggest a new basic structure for symmetric and asymmetric cascaded topologies with reduced number of power electronic components. This topology generates 10 voltage steps by three unequal dc voltage sources and seven switches. The suggested topology creates just positive and zero voltage steps and it needs to one H-bridge to generate negative voltage levels. Based on the located H-bridge, two different cascaded multilevel topologies are proposed. Also, various methods to specify the magnitudes of dc voltage sources are suggested. The proposed cascaded multilevel inverters in comparison with the conventional cascaded topologies and other new topologies which presented in literature decrease the number of components such as, IGBTs, switches, driver circuits and DC links. PSCAD/EMTDC simulations results of 19-level inverter are presented to reconfirm the correct performance of the suggested topologies.

In this article, for studying the effect of inductor coupling on stability of dc-dc converter and controller designing, a sample 4-passive element Cuk dc-dc converter has been analyzed and two kinds of its models (split and coupled inductor models) have been considered. The coupled inductors offer a number of advantages over split inductors, including reduced size, and weight, and having zero ripple current on all windings. So, in this paper, the coupled inductors versus split inductors are investigated from intrinsic stability point of view in Cuk dc-dc converter. In order to study the intrinsic stability, four stability analysis methods including root locus analysis, Bode diagram, Nyquist diagram, and Nichols diagram are used.

During a few decades many multilevel topologies have been proposed. Contemporary research has engaged for new multilevel inverter topology by unique circuits. This paper presents a new sub-module inverter for cascaded multilevel inverters with reduced number of count. The recommended inverter generates 17 step by four DC links (only two DC link are unequal) and 8 power switches. The suggested sub-module inverter generates all voltage levels (positive, negative and zero) at the output without any additional circuit. Also, a cascaded connection for suggested structure is proposed. The advantages of the suggested cascaded connection are reduction number of components such as semiconductor switches, driver, IGBTs, the variety of the value of DC links and DC links in comparison with classical cascaded structures and other new structures which presented in literatures. For specifying the magnitudes of the DC links three new methods are calculated in order to produce more voltage steps, too. PSCAD/EMTDC simulation outcome are demonstrated to confirm the suggested structure excellent operation.

In this paper, a new basic unit is proposed for cascaded multilevel inverter (CMI) to improve the multilevel inverter performance to overcome to their disadvantages. The two topologies of multilevel inverters are proposed by the proposed basic unit. The proposed cascaded topologies consist of two parts. The one is basic unit and another one is H-bridge. Basic units are used to generate zero and positive voltage levels, and negative level is achieved by H-bridge. The proposed topologies have less number of power electronic switches and dc voltage sources. The validity and correct operating of proposed topologies are examined by experimental results for 31-level inverter.

In this paper, a new switched-inductor Z-source inverter topology based on two batteries is proposed. In this topology, two batteries are used to improve the performance of the Z-source inverter with Maximum constant boost control method (CBC) is improved by using two batteries. It is paid more attention to apply suitable power electronic converters to increasing the power level and adaptation the energy level of renewable sources which are recieved so much attention in power generation, to the requierment of consumer network. The proposed toplogy with the capability of increasing power and converting it in one-bridge and storing energy in system by using maximum constant boost control method is presented. The advantages of the this control method are reducing the total cost of the inverter and decreasing inductor current ripple. The performance of the proposed topology with maximum constant boost control method (CBC) in different its duty cycle will investigate and the calculated equations is reconfirmed through EMTDC/PSCAD simulation results.

In this paper, a new switched-inductor Z-source inverter topology using two batteries is proposed. This inverter is capable of increasing the output voltage level in comparison to the other structures of Z-source inverter in lower duty cycle. As a result, the proposed topology is more effective in improvment of the output power quality. The other advantage of the proposed topology is reducing the voltage levels in the case of e lower ac power applications. Because of its higher voltage gain compared to conventional Z-source inverters, this inverter is suitable for distributed generation with renewable resources. The performance of the proposed topology with maximum boost control method (MBC) will be investigated and the calculated equations is reconfirmed through EMTDC/PSCAD simulation results.

In this paper an asymmetric cascaded multilevel inverter based on using a capacitor as one of its input voltage sources is proposed. This inverter is also provided to use charge balance control methods. In order to generate all voltage levels (even and odd) at the output, two different algorithms are proposed to determine the magnitude of the dc voltage sources. The main advantage of this topology is reducing the substitution of dc voltage sources and so decreasing the inverter maintenance cost. The ability of the proposed topology in generation all voltage levels by using charge balance control methods is verified by PSCAD/EMTDC simulation results on a 15-level inverter.