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91.
In this article, a novel design of single layer, compact, multiple input multiple output (MIMO) half‐mode substrate integrated waveguide (HMSIW) cavity backed quad element slot antenna with high front‐to‐back ratio (FTBR) is proposed. The proposed antenna consists of four rectangular SIW cavities with semi‐taper radiating slots. The antenna elements are placed in a fashion to achieve high isolation. This antenna is designed for WLAN vehicular communication system to cover the frequency range of 5.84 GHz to 5.96 GHz. It has high front to back ratio (FTBR) of more than 25 dB without using any external metallic reflector. It has more than 37 dB isolation in between orthogonal elements and more than 24 dB in between parallel elements. The envelop correlation coefficient (ECC) and diversity gain are 0.003 and 9.99 dB respectively in between all the elements. Moreover, the antenna has high gain and efficiency of more than 8 dB and 94%, respectively, in 10 dB impedance bandwidth. It can be tuned in a wide range of frequency. 相似文献
92.
In this paper, a methodology is proposed to determine the design space for synthesis, analysis, and optimization of solar water heating systems. The proposed methodology incorporates different design constraints to identify all possible designs or a design space on a collector area vs. storage volume diagram. The design space is represented by tracing constant solar fraction lines on a collector area vs. storage volume diagram. It has been observed that there exists a minimum as well as a maximum storage volume for a given solar fraction and collector area. Similarly existence of a minimum and a maximum collector area is also observed for a fixed solar fraction and storage volume. For multi-objective optimization, a Pareto optimal region is also identified. Based on the identified design space, the solar water heating system is optimized by minimizing annual life cycle cost. Due to uncertainty in solar insolation, system parameters and cost data, global optimization may not be utilized to represent a meaningful design. To overcome this, a region of possible design configurations is also identified in this paper. 相似文献
93.
Das Bidyut Majumder Mukta Phadikar Santanu Sekh Arif Ahmed 《Multimedia Tools and Applications》2021,80(21-23):31907-31925
Multimedia Tools and Applications - Multiple-choice questions (MCQs) are used as instrumental tool for assessment, not only in various competitive examinations but also in contemporary information... 相似文献
94.
Saibal Ray Tapas Kumar Bhattacharya Vivek Kumar Singh Debabrata Deb Shounak Ghosh Santanu Das 《Ceramics International》2021,47(1):858-864
We report the synthesis of nanocrystalline calcium carbonate with varying particle sizes by precipitation techniques from an aqueous solution of calcium nitrate and sodium carbonate at controlled pH. The particle size of the carbonate powder was precisely controlled by changing the precursor concentration. The synthesized carbonate powders were characterized by using scanning electron microscopy, X-ray diffraction technique, and transmission electron microscopy. The particle size, along with the crystallite size of as-synthesized carbonate powder, decreases with increasing precursor concentration. The non-isothermal decomposition kinetics of the carbonate powder was also evaluated by using near to the modified Arrhenius equation's exact solution. The experimental results were best fitted at n = 0.5, and the one-dimensional diffusion-controlled transport process mechanism (D1) and one-dimensional phase boundary movement mechanism (R1) was found to be very close fit of the corresponding evaluated g(α) value. The apparent activation energy of the nano calcium carbonate decomposition was found in the range of 120–175 kJ/mol, which is also inherently functioning with the average particle size. The apparent activation energy of decomposition of CaCO3 found to be decreased with decreasing average particle size of nanocrystalline calcium carbonate. 相似文献
95.
96.
Jose Belisario Santanu Mondal Iman Khakpour Alexander Franco Hernandez Andriy Durygin Zhe Cheng 《Journal of the European Ceramic Society》2021,41(4):2215-2225
(Hf1-xZrx)B2 solid solution powders were synthesized by two methods. First, solution-based processing of HfCl4, ZrCl4, sucrose, and H3BO3 was conducted followed by heat treatment in Argon to carry out the carbothermal reduction (CTR) reaction to form the diboride powders. Alternatively, in the so-called borohydride reduction (BHR) method, HfCl4, ZrCl4 and NaBH4 were mixed in an Argon glove box followed by heat treatment in Argon at 700?1500 °C. The synthesized powders were characterized by XRD, SEM, TEM, EDS, and TGA, and the influence of different parameters such as starting composition, heat treatment temperature and time on products characteristics were revealed. Both CTR and BHR solid solution powders were then consolidated within ~5 min in a homemade flash sintering (FS) setup. The composition, microstructure, hardness, and thermal-oxidation properties of flash sintered ceramics were characterized, and the implication of this study and directions for future research were discussed. 相似文献
97.
Biocompatible,stimuli‐responsive hydrogel of chemically crosslinked β‐cyclodextrin as amoxicillin carrier
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A novel pH‐responsive, chemically crosslinked hydrogelator (cl‐β‐CD/pVP) has been fabricated using β‐cyclodextrin (β‐CD) and N‐vinyl pyrollidone (N‐VP) in presence of diurethane dimethacrylate (DUDMA) crosslinker/azobisisobutyronitrile initiator through free radical polymerization. Various grades of cl‐β‐CD/pVP have been synthesized and the best grade has been considered with higher crosslinking density, higher gel strength, and lower % swelling ratio. The hydrogelator has been characterized by FTIR, 1H and 13C NMR spectroscopy, TGA, and FESEM analyses. The hydrogelator demonstrates pH‐responsive behavior, which has been confirmed by swelling behavior and gel characteristics at various pH (at 37 °C). Using hen egg lysozyme, degradation experiment has been performed, which confirms the biodegradable nature of the hydrogel. The in vitro cytotoxicity study and live–dead assay suggest that the hydrogelator is cytocompatible toward MG‐63 cells. Finally, the hydrogelator shows excellent efficacy as an antibiotic (amoxicillin) carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45939. 相似文献
98.
Pluronic‐based dual‐stimuli sensitive polymers capable of thermal gelation and pH‐dependent degradation for in situ biomedical application
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Chang‐Hee Whang Hyung Kyung Lee Santanu Kundu S. Narasimha Murthy Seongbong Jo 《应用聚合物科学杂志》2018,135(31)
Thermo‐sensitive hydrogels are considered ideal for applications in the biomedical fields for their biocompatibility, flexibility, tissue‐like water content, and reversible gelation property. By adjusting sufficient hydrophilic–hydrophobic balance in block copolymer structure, thermogel's critical gelation temperature (CGT) can be modified to be near the physiological temperature, which makes it an appealing candidate for in situ gel depot. In this study, we report successful syntheses of novel multiple block copolymer compounds, denoted as dual‐stimuli sensitive polymers (DSSPs), by copolymerizing Pluronic P104 (7100 Da) and 2,2‐bis(aminoethoxy)propane (BAP) using diisocyanate linkers, l ‐lysine ethyl ester diisocyanate (DSSP‐1), and 1,6‐hexamethylene diisocyanate (DSSP‐2). Through effective elongation of polymer chain lengths (DSSP‐1: 41,760 Da, DSSP‐2: 41,230 Da), Pluronic P104's reversible thermal gelation properties were enhanced, as demonstrated by lowered CGTs (DSSP‐1: 36 °C, DSSP‐2: 38.7 °C; 15 wt %) that is near the physiological temperature. Furthermore, integration of acid‐labile BAP allowed rapid pH‐dependent degradation of the polymer, which was displayed by gel permeation chromatography and release profiles of nile red and irinotecan from polymeric micelles and gels, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46552. 相似文献
99.
Himadri Mukherjee Sk. Md. Obaidullah K. C. Santosh Santanu Phadikar Kaushik Roy 《International Journal of Speech Technology》2018,21(4):753-760
Voice activity detection (VAD) refers to the task of identifying vocal segments from an audio clip. It helps in reducing the computational overhead as well elevate the recognition performance of speech-based systems by helping to discard the non vocal portions from an input signal. In this paper, a VAD technique is presented that uses line spectral frequency-based statistical features namely LSF-S coupled with extreme learning-based classification. The experiments were performed on a database of more than 350 h consisting of data from multifarious sources. We have obtained an encouraging overall accuracy of 99.43%. 相似文献
100.
Trap‐State Suppression and Improved Charge Transport in PbS Quantum Dot Solar Cells with Synergistic Mixed‐Ligand Treatments
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Santanu Pradhan Alexandros Stavrinadis Shuchi Gupta Yu Bi Francesco Di Stasio Gerasimos Konstantatos 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(21)
The power conversion efficiency of colloidal PbS‐quantum‐dot (QD)‐based solar cells is significantly hampered by lower‐than‐expected open circuit voltage (VOC). The VOC deficit is considerably higher in QD‐based solar cells compared to other types of existing solar cells due to in‐gap trap‐induced bulk recombination of photogenerated carriers. Here, this study reports a ligand exchange procedure based on a mixture of zinc iodide and 3‐mercaptopropyonic acid to reduce the VOC deficit without compromising the high current density. This layer‐by‐layer solid state ligand exchange treatment enhances the photovoltaic performance from 6.62 to 9.92% with a significant improvement in VOC from 0.58 to 0.66 V. This study further employs optoelectronic characterization, X‐ray photoelectron spectroscopy, and photoluminescence spectroscopy to understand the origin of VOC improvement. The mixed‐ligand treatment reduces the sub‐bandgap traps and significantly reduces bulk recombination in the devices. 相似文献