Recent advances in micro-electromechanical (MEMS) technology have led to the development of small, low-cost, and low-power sensors. Wireless sensor networks (WSNs) are large-scale networks of such sensors, dedicated to observing and monitoring various aspects of the physical world. In such networks, data from each sensor is agglomerated using data fusion to form a single meaningful result, which makes time synchronization between sensors highly desirable. This paper surveys and evaluates existing clock synchronization protocols based on a palette of factors like precision, accuracy, cost, and complexity. The design considerations presented here can help developers either in choosing an existing synchronization protocol or in defining a new protocol that is best suited to the specific needs of a sensor-network application. Finally, the survey provides a valuable framework by which designers can compare new and existing synchronization protocols. 相似文献
The various toxic contaminants such as dyes, heavy metals, pesticides, rare‐earth elements, and hazardous chemicals are the major threats to all the flora and fauna. Owing to the harmful ill effects caused by the toxic contaminants, it is necessary to eliminate these compounds from the authors’ ecosystem. The chitosan magnetic nanomaterials (CMNPs) are one of the superior materials used in the wastewater treatment through various conventional technologies. The chitosan is a natural source obtained from the crustacean shells of crabs, prawns etc. The magnetic nanomaterial prepared by the reinforcement of chitosan is highly effective in the removal of heavy metals, dyes, organic matter, and harmful chemicals. It is used in various technologies such as adsorption, flocculation, immobilisation, photocatalytic technology, and bioremediation. This possesses unique surface and magnetic characteristics, Moreover, it is simple, economically feasible, and eco‐friendly material used efficiently in wastewater treatment. This review paper depicts the overview of CMNP in the industrial effluent treatment.Inspec keywords: effluents, adsorption, dyes, water pollution control, wastewater treatment, nanofabrication, nanoparticles, catalysis, industrial waste, photochemistry, flocculation, contamination, magnetic particlesOther keywords: CMNPs, water pollution control, toxic contaminants, dyes, heavy metals, pesticides, rare‐earth elements, hazardous chemicals, flora, fauna, chitosan magnetic nanomaterials, wastewater treatment, natural source, magnetic nanomaterial, organic matter, harmful chemicals, photocatalytic technology, magnetic characteristics, eco‐friendly material, industrial effluent treatment相似文献
In this paper, a dual‐band zeroth order resonance (ZOR) circularly polarized epsilon negative antenna is proposed for the case where shunt ZOR (fsh ) is higher than series ZOR (fse ). Epsilon negative unit cells resonate fsh , while a pseudo‐open termination unit cell with a series capacitance resonate fse , resulting in a dual‐band ZOR. The pseudo‐open termination unit cell can be placed anywhere around the epsilon negative unit cells for proper matching. Circular polarization (CP) is achieved by creating orthogonal components using asymmetric unit cells (AUCs). Zeroth order resonator inherently provides 90° phase shift between two orthogonal polarizations. Left hand circular polarization (LHCP) is achieved by adding stubs to the unit cells with two 90° right bends. Electric field distribution is used to verify the resonances for zeroth order and it is found that both the resonances follow zeroth order characteristics. The measured resonances are 4.11 GHz (fse ) and 4.60 GHz (fsh ) with measured average axial ratio of 2.4 dB at fse and 1.5 dB at fsh , respectively. The measured LHCP peak gain for fse is 1.53 dBic and for fsh is 2.34 dBic. The proposed design covers a frequency range of 3.6 to 4.6 GHz by varying the length of the stubs. 相似文献
Objective: In this study, we investigated the potential of thiolated chitosan-based mucoadhesive film, loaded with risedronate sodium in the treatment of osteoporosis.
Significance: Risedronate sodium is a bisphosphonate derivative having very low bioavailability when administered through the oral route. Moreover, the adverse effects associated with the drug when administered through GIT necessitate an alternative and feasible route which can improve its bioavailability and therapeutic efficacy.
Methods: Thiolation of chitosan was interpreted by different analytical techniques. The mucoadhesive films were prepared by the solvent evaporation method and evaluated for drug content analysis, swelling degree, mucoadhesive parameters, and permeation characterization. For the screening of preclinical efficacy and pharmacodynamic parameters, a methylprednisolone induced osteoporotic rat model was used. The trabecular microarchitecture and biochemical markers were evaluated for determination of bone resorption.
Results: The different analytical characterization of synthesized thiolated chitosan revealed that chitosan was successfully incorporated with thiol groups. The formulation containing 2:1 ratio of thiolated chitosan and HPMC-4KM was found to have the maximum swelling degree, mucoadhesive strength with a good force of adhesion and better in vitro permeability compared to the marketed formulation. With respect to trabecular microarchitecture, the drug-loaded film formulation showed superior and promising results. Furthermore, the film formulation also improved the serum level of biomarkers better than the marketed formulation.
Conclusions: The results significantly suggest that risedronate loaded novel mucoadhesive film formulation could be a logical approach in the therapeutic intervention of osteoporosis. 相似文献
Over past few decades, the electronic boards density and performance are enhanced by entrenching the components in the interior surfaces of the printed circuit boards (PCBs).The worthiness of this novel innovation has to be probed to warranty the functioning of electronic boards acquiesced to callous environments. In this study, a novel advancement concentrating on the development of bio-based materials for the PCB applications has been documented. The bio-based composite from rice husk-epoxy resin could impendingly substitute the conventional synthetic fiber reinforced epoxy composites in PCB applications. The essential properties of biocomposites were assessed such as tensile and bending properties, dielectric property, thermal properties, moisture absorption, microdrilling, biodegradability, and flammability. Results obtained found that, these biocomposites were promising for PCB application. 相似文献
Multimedia Tools and Applications - The color image enhancement algorithm proposed here yields an improvement of the image data that suppresses undesired distortions or enhances some image features... 相似文献
In present digital era, multimedia like images, text, documents and videos plays a vital role, therefore due to increase in usage of digital data; there comes high demand of security. Encryption is a technique used to secure and protect the images from unfair means. In cryptography, chaotic maps play an important role in forming strong and effective encryption algorithm. In this paper 3D chaotic logistic map with DNA encoding is used for confusion and diffusion of image pixels. Additionally, three symmetric keys are used to initialize 3D chaos logistic map, which makes the encryption algorithm strong. The symmetric keys used are 32 bit ASCII key, Chebyshev chaotic key and prime key. The algorithm first applies 3D non-linear logistic chaotic map with three symmetric keys in order to generate initial conditions. These conditions are then used in image row and column permutation to create randomness in pixels. The third chaotic sequence generated by 3D map is used to generate key image. Diffusion of these random pixels are done using DNA encoding; further XOR logical operation is applied between DNA encoded input image and key image. Analysis parameters like NPCR, UACI, entropy, histogram, chi-square test and correlation are calculated for proposed algorithm and also compared with different existing encryption methods.
Medical image segmentation is crucial for neuroscience research and computer-aided diagnosis. However, intensity inhomogeneity and existence of noise in magnetic resonance images lead to incorrect segmentation. In this article, an effective method called enhanced fuzzy level set algorithm is presented to segment the white matter, gray matter, and cerebrospinal fluid automatically in contrast-enhanced brain images. In this method, first, exposure threshold is computed to divide the input histogram into two sub-histograms of different gray levels. The input histogram is clipped using a mean gray level to control the excessive enhancement rate. Then, these two sub-histograms are modified and equalized independently to get a better contrast enhanced image. Finally, an enhanced fuzzy level set algorithm is employed to facilitate image segmentation. The extensive experimental results proved the outstanding performance of the proposed algorithm compared with other existing methods. The results conform its effectiveness for MR brain image segmentation. 相似文献
