Optimal electromechanical bandgaps in piezo-embedded mechanical metamaterials

Elastic mechanical metamaterials are the exemplar of periodic structures. These are artificially designed structures having idiosyncratic physical properties like negative mass and negative Young’s modulus in specific frequency ranges. These extreme physical properties are due to the spatial periodicity of mechanical unit cells, which exhibit local resonance. That is why scientists are researching the dynamics of these structures for decades. This unusual dynamic behavior is frequency contingent, which modulates wave propagation through these structures. Locally resonant units in the designed metamaterial facilitate bandgap formation virtually at any frequency for wavelengths much higher than the lattice length of a unit. Here, we analyze the band structure of piezo-embedded negative mass metamaterial using the generalized Bloch theorem. For a finite number of the metamaterial units coupled equation of motion of the system is deduced, considering purely resistive and shunted inductor energy harvesting circuits. Successively, the voltage and power produced by piezoelectric material along with transmissibility of the system are computed using the backward substitution method. The addition of the piezoelectric material at the resonating unit increases the complexity of the solution. The results elucidate, the insertion of the piezoelectric material in the resonating unit provides better tunability in the band structure for simultaneous energy harvesting and vibration attenuation. Non-dimensional analysis of the system gives physical parameters that govern the formation of mechanical and electromechanical bandgaps. Optimized numerical values of these system parameters are also found for maximum first attenuation bandwidth. Thus, broader bandgap generation enhances vibration attenuation, and energy harvesting can be simultaneously available, making these structures multifunctional. This exploration can be considered as a step towards the active elastic mechanical metamaterials design

Vegetable Cultivation under Hydroponics in Himalayas : Challenges and Opportunities

Defence Institute of Bio-Energy Research, Haldwani has successfully developed a hydroponics system by clubbing the soil less cultivation with rain water harvesting technology. The institute has also developed a suitable nutrient composition suitable for wide range of vegetables. Among the various varieties/hybrids grown in hydroponics, cucumber line PC 4C-8 exhibited the maximum fruit yield (448.3 q/ha). Among the various tomato hybrids, Avinash-2 exhibited highest yield (1052 q/ha) and number of fruits (154 per sq m) whereas TSS, total sugars, crude protein and minerals content were the maximum in tomato hybrid DARL-304. Interestingly, hydroponics system prolonged the harvesting period by 45 days in tomato. Plant population density of 6 plants/m2 was found optimum with the highest fruit yield in tomato and cucumber. Tomato hybrid DARL-304 exhibited higher fruit yield (6.5 kg/plant). Hydroponics system have been found successful in Auli (9000’ MSL), Joshimath with fruit yield of 2.25 kg/plant to 3.79 kg/plant in tomato. The yield was higher in rain water as comparison to river water. The article deals with the hydroponics technology in detail vis-à-vis efforts made at DIBER for standardization of hydroponics technology. It is envisaged that experience gained in successful cultivation of various crops in hydroponics using single nutrient solution at various altitudes through research stations of the institute

Effect of Multiple Rounds of Mass Drug Administration under Lymphatic Filariasis Elimination Program on Prevalence of Soil-Transmitted Helminthiasis in One of the Co-endemic Districts of India

Both soil-transmitted helminthiasis and lymphatic filariasis are co-endemic in some districts of India. The study was aimed at comparing the prevalence of soil-transmitted helminthiasis (STH) infection before and after mass drug administration (MDA) given for lymphatic filariasis at Alappuzha.We examined stool samples of 219 children aged between 9 and 10 years from nine schools at Alappuzha, Kerala, in June 2015. The current STH situation was compared with that in the year 1999 (before the institution of MDA) in the same age group in the same district. WHO-recommended Kato-Katz technique was used for STH prevalence estimation. Information regarding socio-demographic variables, sanitation, personal hygiene practices was also recorded. Chi-square test was used to study association of risk factors with STH infection.A total of 79 (36.07%) children were found to be positive for STH infection. Out of all samples positive for Ascaris lumbricoides, 4 (5%) were found co-infected with Trichuris trichiura and none with hookworm. Factors like absence of household latrine, lack of hand washing before meals and practice of consumingunwashed fruits were found to be significantly associated with occurrence of STH infection.Over the years, consecutive rounds of MDA for LF have led to a decline in intestinal worm burden but with little effect on the overall prevalence of STH. Thus, STH control activities working synergistically with the Filarial Elimination Strategy can yield better results in the co-endemic areas with optimum resourceutilization

A Critical Analysis of Fraud Cases on the Internet

We lived in the era of technology, where online websites have made communication and interaction much easier than the early decade. The modern world is changing so quickly, and emerging new trends simplify our lives, but on the other hand, it will also create risks. A website acts as a more admired platform by the user to access the different web applications. Because of the functions of the website, all the data on the website is available in the proper structure, which makes the working environment much convenient and efficient. The websites may undoubtedly be a precious resource for young people, but it may also cause severe problems. It is really easy to build a fake website that looks like an original website where hackers like to deceive consumers and businesses for their own benefits. In this paper, researchers have examined online fraud cases through web applications and how fraudulent websites affect financial loss. Researchers also highlighted the current situation regarding the usage of online services, as well as the threats that have an impact on users. In addition, researchers have suggested that new laws and regulations will be implemented for preventing cybercrime

PCM-assisted energy storage systems for solar-thermal applications: Review of the associated problems and their mitigation strategies

Latent heat energy storage (LHES) system is identified as one of the major research areas in recent years to be used in various solar-thermal applications. However, there are various challenges associated i.e., low thermal conductivity, leakage issues, stabilization concerns, etc. In this work, a comprehensive review of studies dealing with these problems and their mitigation strategies. Various design parameters influencing the performance of PCM-assisted systems are also discussed. This article further presents a detailed review of several mathematical models, based on system enthalpy and heat capacity-based modeling schemes along with the techno-economic analysis. The review results reflect the application of porous foams increasing thermal conductivity values of PCM composites relative to pure PCM working mediums. Moreover, the use of extended surfaces with appropriate geometries reduces the phase transition durations for the working medium significantly which enhances the thermal performance. Additionally, PCM encapsulations are identified as one of the widely accepted procedures intensifying the thermal performance of energy storage systems. However, the selection of appropriate encapsulation shell material and shell geometries are some of the important factors to be considered to ensure optimum system performance. This review focuses on the significant aspects of PCM encapsulation design parameters for several solar-thermal systems

Development and Evaluation of Active Case Detection Methods to Support Visceral Leishmaniasis Elimination in India.

As India moves toward the elimination of visceral leishmaniasis (VL) as a public health problem, comprehensive timely case detection has become increasingly important, in order to reduce the period of infectivity and control outbreaks. During the 2000s, localized research studies suggested that a large percentage of VL cases were never reported in government data. However, assessments conducted from 2013 to 2015 indicated that 85% or more of confirmed cases were eventually captured and reported in surveillance data, albeit with significant delays before diagnosis. Based on methods developed during these assessments, the CARE India team evolved new strategies for active case detection (ACD), applicable at large scale while being sufficiently effective in reducing time to diagnosis. Active case searches are triggered by the report of a confirmed VL case, and comprise two major search mechanisms: 1) case identification based on the index case's knowledge of other known VL cases and searches in nearby houses (snowballing); and 2) sustained contact over time with a range of private providers, both formal and informal. Simultaneously, house-to-house searches were conducted in 142 villages of 47 blocks during this period. We analyzed data from 5030 VL patients reported in Bihar from January 2018 through July 2019. Of these 3033 were detected passively and 1997 via ACD (15 (0.8%) via house-to-house and 1982 (99.2%) by light touch ACD methods). We constructed multinomial logistic regression models comparing time intervals to diagnosis (30-59, 60-89 and ≥90 days with =90 days compared to the referent of <30 days for ACD vs PCD were 0.88, 0.56 and 0.42 respectively. These ACD strategies not only reduce time to diagnosis, and thus risk of transmission, but also ensure that there is a double check on the proportion of cases actually getting captured. Such a process can supplement passive case detection efforts that must go on, possibly perpetually, even after elimination as a public health problem is achieved