Sharif Digital Repository

This paper proposes a family of interleaved DC-DC converters for high step-up applications based on multi-winding coupled inductors, which utilize inductive and capacitive approaches to transfer the input energy to the output load. The wide output load voltage level of the proposed converter depends on the switches duty cycle and the coupled inductor (CI) turns ratio. As some features, interleaving and cascading help the converters achieve high output voltage gain, low input current ripple, low-volume input inductor, and high reliability. Moreover, employing multi-winding coupled inductors improves output voltage gain, recycles the magnetic components stored energy, cancels circulating... 

In this paper, a single-inductor dual-output (SIDO) DC/DC converter is proposed. The significant feature of the proposed converter is feeding a constant power load in low voltage side (LVS) port, where even feeding a variable load at LVS doesn't have any cross regulation to high voltage side port with the desired approximation. Magnificently, both merits are obtained in open-loop manner which is an outstanding characteristic in comparison with existed converters. In this paper, soft commutation and soft switching of switches and diodes are investigated along with the aforementioned main novelty. Moreover, detailed theoretical analyses of the proposed SIDO DC/DC converter in continuous... 

In this paper, a new interleaved DC–DC converter based on a coupled and a single input inductor is proposed. The suggested high step-up converter utilizes various inductive and capacitive methods to transfer magnetic energy more efficiently. The output voltage is regulated with the switches' duty cycle and the coupled inductor (CI) turns ratio, which provide a wide output voltage range. Interleaving improves the converter reliability, employs both the first and third areas of CI's B-H plane, cancels DC component of the CI, and reduces the input current ripple of the proposed converter with twice switching frequency. Utilization of two output ports for voltage stress and ripple reduction in... 

A high step-up converter including one active switch is presented in the present work. The introduced structure is a combination of Quadratic boost converter and Zeta converter; therefore, it features low input and output current ripples. The energy of leakage inductor is inherently recovered and the voltage spike on switch is perfectly mitigated. The voltage across diodes and switch is quite lower than the boosted output voltage which can be a prominent issue in high step-up converters. This can lead to employ switches and diodes with low conduction losses causing overall efficiency to increase. The converter function in CCM and DCM are analyzed, and the voltage conversion ratio along with... 

This paper investigates the metallurgical factors that contributed to the failure of several cast U-clamps made of HK40 steel U-clamps during the installation of a pre-startup heater in a petrochemical plant. The presence of extensive macro/micro-shrinkage porosity is identified as the root cause of the failure. The severe shrinkage-related porosity in the material, confirmed by metallographic examination and non-destructive X-ray radiography testing and evidenced by a severe loss in tensile ductility, resulted in a unique fully dendritic fracture surface characteristic. It was found that the loss of structural integrity associated with macro-shrinkage voids and loss of toughness associated... 

In this paper, a new extended quasi-switched Z-source inverter, using a switched-inductor cell, is proposed. The most important advantage of the proposed inverter is achieving the maximum voltage gain in the lower duty cycle with less circuit components than similar previous inverters, which causes the modulation index value increase. Furthermore, it leads to less power losses and less voltage and current ripples. The employed control method in this inverter is the pulse width modulation (PWM) simple boost control method. In this paper, theoretical analysis and comparison results of the proposed inverter with other similar ones are prepared. In addition, the experimental results reconfirm... 

Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar  

SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity  

In this paper, we consider an integrated sensing and communication (ISAC) system with wireless power transfer (WPT) where an unmanned aerial vehicle (UAV)-based radar serves a group of energy-limited communication users in addition to its sensing functionality. In this architecture, the radar senses the environment in phase 1 (namely sensing phase) and mean-while, the communications users (nodes) harvest and store the energy from the radar transmit signal. The stored energy is then used for information transmission from the nodes to UAV in phase 2, i.e., uplink phase. Performance of the radar system depends on the transmit signal as well as the receive filter; the energy of the transmit... 

One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function... 

Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance... 

It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive... 

There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas  

By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only... 

One of the most important obstacles in passive radar applications is removing the direct signal from the target channel. Otherwise, week echoes from the targets in the target channel would be ignored due to the limited dynamic range of the system. One of the most effective techniques in this field is using adaptive filters. In this paper various adaptive filters are introduced and their performances are shown and compared  

It has been shown that using multiple antennas in a radar system improves the performance considerably, since multiple target echoes are received from different aspect angles of the target. In this way, the target detection is improved. However, when using multiple antennas, some problems, such as designing the transmit signals, synchronization, etc. emerge that should be solved. One of such problems is the receiver placement. Receiver placement deals with choosing a proper position for the receive antenna in order to optimize the whole system's performance. In this paper, a receiver placement procedure based on improving the radar ambiguity function is proposed for the case of a multisite... 

By employing the MIMO (multiple-input-multiple-output) technology in radar, some new problems emerged, that, in order to benefit the MIMO gains in radar, it was necessary to solve them suitably. One of such obstacles is determining the positions of receive antennas in a MIMO radar system with widely separated antennas (WS MIMO radar), since it is shown that the antennas' positions affect the whole system's performance considerably. In this study, a proper receivers' positioning procedure is proposed. To do this end, four criteria are developed based on the proposed MIMO detector and the MIMO ambiguity function. The simulations verify that the proposed positioning procedure improves the... 

Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields  

Carbon capture is crucial for mitigating climate change and achieving global emissions reduction targets. Among various technologies, absorption-based methods using aqueous solvents are among the most common and efficient, offering high capture rates and retrofit capabilities for existing industrial facilities. However, selecting the optimal solvent is challenging due to its direct impact on the performance, efficiency, and cost-effectiveness of the carbon capture process. This research introduces a novel multi-class classification methodology for solvent selection in carbon capture. Leveraging a dataset of 656 data points, including features such as temperature, pressure, molar ratio, and... 

Purpose: Intensive actions implemented to alleviate poverty created many challenges. Millions of people face acute food insecurity; hence, food production needs to be increased to feed the existing and increasing population through sustainable agricultural practices. Sustainable agricultural development is the only way forward to assist humanity. Research Method: TExisting literature on sustainable agriculture was reviewed, explored, understood, described, evaluated, and synthesized and their relationships to sustain smallholder farmers were analyzed. Findings: Technological innovations in increasing resource use efficiency, modern breeding techniques, and renewable energy sources aid in...