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This paper proposes a distributed finite-time secondary controller to achieve average voltage regulation and proportionate current sharing within a finite settling time for autonomous network of dc microgrids. It is employed by using a distributed finite-time control approach which maintains average voltage regulation of the system facilitating proportionate current sharing simultaneously by virtue of dynamic consensus between its neighbors. The proposed scheme ensures an improved performance over the conventional distributed secondary methods by reducing overshoots and chattering which is significant for critical operation of the loads. The proposed control strategy is simulated in MATLAB/Simulink environment to test link-failure resiliency, plug and play capability, and controller performance under communication delays within a tolerable upper bound on delay determined using time-delay analysis. Moreover the effect of variable time delays in different transmission medium is also simulated to test the practicality of the approach. This strategy is further tested on a 500-W FPGA-based experimental prototype to validate the control approach under different scenarios.

Production of biomass and phycocyanin (PC) were investigated in highly pigmented variants of the unicellular rhodophyte Galdieria sulphuraria, which maintained high specific pigment concentrations when grown heterotrophically in darkness. The parental culture, G. sulphuraria 074G was grown on solidified growth media, and intensely coloured colonies were isolated and grown in high-cell-density fed-batch and continuous-flow cultures. These cultures contained 80-110 g L(-1) biomass and 1.4-2.9 g L(-1) PC. The volumetric PC production rates were 0.5-0.9 g L(-1) day(-1). The PC production rates were 11-21 times higher than previously reported for heterotrophic G. sulphuraria 074G grown on glucose and 20-287 times higher than found in phototrophic cultures of Spirulina platensis, the organism presently used for commercial production of PC.

Chaotic switching is a newly evolve randomization method which suppress the conducted electromagnetic interference generated within the DC-DC converter. It can also suppress the spectral peaks present in the frequency band effectively by spread spectrum technique and spread it over the wide range of frequency band implying electromagnetic interference (EMI) suppression. In this article, a chaotic pulse width modulation technique based on randomized carrier frequency modulation with fixed duty ratio is generated through field programable gate array for suppressing the conducted electromagnetic interference generated within the Luo-converter. A hardware prototype of Luo-converter is developed in order to analyze EMI reduction through power spectral density analysis by comparing both traditional periodic PWM switching and chaotic PWM switching. The results obtained from the hardware setup shows significant reduction of EMI with chaotic switching as compared to traditional pulse width modulation switching under both boost and buck operation of Luo-converter.

This study investigated methane yield via anaerobic digestion of multi-component substrates based on mixtures of biodegradable single-component substrates with cow dung as main component. Bench and full-scale digestion experiments were carried out for both single and multi-component substrates to identify the relationship between methane yield and substrate composition. Results from both bench- and full-scale experiments corresponded well and showed that using multi-component substrates increases the methane yield much more than what would be expected from digestion of single substrates. Process stability as indicated by gas production, pH and NH(4)(+) concentration variations were also improved by using multi-component substrates compared to digestion of single-component substrates. The results, thus, suggest that assessment of methane yield for multi-component substrates cannot reliably be based on methane yields for corresponding single-component substrates but should instead be measured directly.

Increasing energy demand and the fast depletion of fossil fuels have prompted the quest for sustainable energy sources. Biodiesel is a potential fossil fuel replacement that can be used in engines without modification. However, the commercial feasibility of biodiesel production is a major challenge. A resilient and cost-efficient biodiesel supply chain network is essential for commercialization. In addition, disruption risks arising from operational downtime, labor strikes, natural disasters, and uncertainty embedded in the data compromise the effectiveness of tactical and strategic level supply chain planning. In line with these requirements, an animal fat-based biodiesel supply chain model that reduces the total system cost and accounts for both disruption and operational risks is proposed. The proposed model determines the optimal production–distribution quantities and supports facility location and capacity decisions against multiple supply and demand interruption scenarios. A novel interactive solution technique, robust possibilistic flexible programming, which enables decision-makers to incorporate flexibility into model constraints, has been introduced. Furthermore, a p-measure constraint that ensures the lowest cost under disruption scenarios is used to control network reliability. A real-world case study is used to assess the suggested model and solution technique's applicability. The findings demonstrate a tradeoff between system reliability and nominal cost, showing that with a marginal increase in overall cost, the decisions can be secured against an uncertain environment. Biodiesel producers and distributors, as well as investors and regulators, may potentially benefit from the proposed model.

This paper describes the characteristic investigation of the Novel Dual-stator V-Shape Magnetic Pole Six-Phase Permanent Magnet Synchronous Generator (NDSVSMPSP-PMSG) for wind power application. The proposed generator has V-shaped embedded magnetic pole in the rotor and six-phase winding in both the stator. The proposed generator has high-power density and high efficiency. For emphasizing the significance of the proposed generator, the characteristics of the NDSVSMPSP generator are analyzed and compared to one of the traditional generators, i.e., the Dual-stator Surface Mounted Six-Phase Permanent Magnet Synchronous Generator (DSSMSP-PMSG). For the design and characteristic investigation of both the generator, Finite Element Method (FEM) is chosen because of its high accuracy. Two modes of FEM analysis are considered, namely magneto-statics and transients. The magneto static analysis is used for the study of flux line and flux density distribution, while the transient analysis is considered for the generator’s characteristic investigation. The performance characteristics such as generated Electromotive Force (EMF) for both inner and outer stator, Percentage Total Harmonic Distortion (THD) of developed voltage, Developed EMF vs rpm, terminal voltage vs. current, developed rotor torque vs time, percent (%) ripple content in torque, and percent efficiency vs current for both generators are investigated. As a result, it can be stated that the power density and reliability of the proposed generator is higher than that of the traditional generator.

The cost efficiency of wireless platforms and their easy deployment enable the applicability of it in widespread application domains. Wireless sensor networks (WSNs) are not excluded from it. Their application domains vary from industrial monitoring to military applications. A WSN is a resource-constrained network and energy of the WSN node is a valuable resource. Like every other network, WSNs are also vulnerable to security attacks. A security attack can results in networks consuming more resources, leading to earlier depletion of node energy. A significant part of the resource consumption in a WSN is controlled by the medium access control (MAC) mechanism. This paper focuses on WSN MAC mechanisms and countermeasures for attacks targeting the MAC layer in a WSN. Denial of sleep attacks are the most relevant for WSN MAC as these types of attacks have shattered effects, which bring down the sensor lifetime from years to days. This paper proposes a secure hybrid MAC mechanism, Green and Secure Hybrid Medium Access Control (GSHMAC) to overcome the devastating effect of WSN MAC attacks. The proposed mechanism provides features such as collision threshold-based MAC mode control and countermeasures on WSN MAC using internal MAC mechanisms. GSHMAC shows improved energy-efficiency, delay, and throughput in the presence of attacks, as compared with state-of-art secure MAC mechanisms.

The heavy earth moving machineries (HEMM) like hydraulic excavator play a major role in construction and mining industries. In this context, the energy saving strategies in hydraulic excavator needs to be addressed considering its vital importance. Since the hydraulic excavators are subjected to heavy loads, hence the opportunity to harness the potential gravitational energy (GPE) remains a key area which can be effectively explored in order to minimize the energy consumption in consideration with hydraulic excavator. In the projected system, the potential energy is stored as pressure energy in hydro-pneumatic accumulator. The upward movement of the boom is executed with the help of prime mover during the starting of the first duty cycle. In the latter duty cycles, the stored pressurized energy is utilized together with the prime mover energy capable to execute the upward movement of the boom. The position of the boom cylinder is controlled by using the conventional PID controller using proportional flow control valve (PFCV) and accumulator. The error between the actual position and demand position of the linear actuator is minimized along with attainment of superior controlled performance while utilizing Model Predictive Controller (MPC). The pressurized accumulator with PFCV has been utilized to cater the different position demands. This has been also justified both experimentally and analytically with the error in the permissible range of 2%. It has been observed that the proposed system is 10% more efficient in contrast to the conventional system.