Narrow Results

The movement of a piston rod in a pneumatic cylinder is directly affected by the air humidity in the atmosphere, especially in the case of piston rods without any means of protection or grease on their surfaces. In a pneumatic cylinder system, the friction between the piston rod and the rod seal is sliding friction, and it has a significant value that varies with the variation in the moisture on the piston rod’s surface. In this paper, an investigation of the friction characteristics of piston rods and rod seals in a pneumatic cylinder was carried out with different humidity and velocity values to understand the effect of lubricants on the moving parts of pneumatic systems in humid environments, where the friction characteristics of the displacements corresponding to the static and dynamic friction forces were displayed on a measuring device. The research results showed that the static friction forces tended to decrease by $10\%÷16\%$ and that the dynamic friction forces tended to decrease by $14\%÷24\%$ when the relative humidity increased from 51% to 99% at different velocities between 5 and 100 mm/s.

Relative humidity is an important parameter. The detection and control of humidity is of great significance for agriculture, new material development, biological research and protection, health services and other industrial and agricultural production. In this paper, a micro-nano photonic crystal fiber humidity sensor with U-shaped structure is proposed. Due to its probe structure, this structure can more conveniently realize the detection work. The experiment shows that this kind of optical sensor has good linearity in the humidity range of 42–62RH%, and can realize the humidity sensing of 27.62pm/RH%. The detection range of this kind of sensor is relatively wide, and can realize the optical fiber sensing in a larger humidity range.

Present study deals with the development of an artificial neural network (ANN)-based technique for tea quality quantification by monitoring fermentation and drying condition of the tea processing stages. An RS485 network-based instrumentation system has been developed and implemented for data collection for these two stages. Three calibrated sensor nodes are installed in the fermentation room due to its larger floor area to collect temperature and relative humidity (RH). Dryer inlet temperature is recorded using a calibrated thermocouple-based sensor node. From seven input parameters and target quality data obtained from tea taster, the ANN model has been developed to find the correlation between the process condition and the tea quality. From the correlation study, more than 90% classification rate is obtained from the model. The model is also validated with some independent data showing more than 60% correlation. Error in terms of root mean square error (RMSE) is about 0.17. This model will be helpful for improvement of tea quality.

Multifractal detrended fluctuation analysis (MF-DFA) for bivariate series has been used to study the auto-correlation between temperature and relative humidity series in Wuhan city, China. The results show that long-range persistence auto-correlation exists between the temperature and relative humidity series and the auto-correlation has multifractal characteristics. For the two climate records, the contribution of single series to multifractality is analyzed by utilizing chi square (${\chi }^2$) test. By comparing the chi square test statistics of original series with those of shuffled and surrogate series, we conclude that the relative humidity is more responsible for the multifractality due to its long-range correlation, and the temperature and relative humidity series almost have the same degree of contributions to the multifractality due to a fatness of probability density function (PDF) correlation. On the whole, the relative humidity series has dominant effect in the auto-correlation.

Corrosion initiation time of steel reinforcement for partially saturated concrete members subjected to chloride ingress is investigated at five places along Indian coasts using simplified probabilistic analysis and sensitivity of the parameters to reinforcement corrosion is studied. Previously proposed diffusion based chloride ingress model for constant surface chloride concentration and variable diffusion coefficient is used. Corrosion is initiated when the chloride concentration on steel reinforcement exceeds a threshold value. The various input parameters considered in the model are surface chloride concentration (C_s), chloride threshold value (C_th), Concrete cover (X), reference diffusion coefficient (D_ref), age (t), reference age (t_ref), diffusion decay index (m) and monthly temperature and relative humidity correction factors f(T) and f(h) respectively; to reference diffusion coefficient. For prediction of corrosion initiation time temperature and relative humidity data collected by India metrological Department is used and all other parameters are assumed same. A large variation in corrosion initiation time is found and therefore it becomes necessary to consider the temperature and relative humidity data in a region. Life-365 considers fully saturated condition of concrete and thus underestimates the corrosion initiation time of a reinforced concrete member. The deterministic approach uses mean values of the parameters and provides a 50% probability of corrosion initiation but the probabilistic approach provides expected time of first corrosion for chosen risk of corrosion and also gives sensitivity of parameters to probability of corrosion. Corrosion initiation time in ascending order is found at Colaba, Kanyakumari, Santacruz, Chennai and Vishakhapatnam. Corrosion initiation time is useful for owner, designer, or to an organization to take decision in time of priority of repairs, repair strategy, corrosion protection in order to optimize maintenance planning and budgeting. Planned maintenance at the optimum time is the safest and most cost effective approach.

In this paper, an evaluation of the influence of atmospheric humidity on the critical buckling load of reinforced concrete columns is performed. A particular case consisting of a real, extremely slender reinforced concrete pole was taken for the study. The chosen mathematical procedure for calculating the critical load is based on the Mechanics of Deformable Solids due to variations of structure vibration frequency over time. The rheological behavior of concrete related to creep and shrinkage, which illustrates the time-dependent aspect of the problem, was also considered in the analysis following normative recommendations from the Brazilian Association of Technical Standards (ABNT). In order to evaluate value changes of critical buckling loads, different time instants after loading the structure as well as different relative humidity from 0% to 100%, in 10% increments were considered. According to the selected criteria, it was possible to verify that a higher atmospheric humidity decreases the water transport from the interior out to the exterior surfaces of concrete, hence positively influencing structure stiffness. Therefore, the lowest reduction on critical buckling was 41.9% at 100% relative atmospheric humidity, versus the highest 60.7% at 0% relative humidity. A period of 7500 days after loading the structure was considered in the analysis.

High moisture content wheat kernels are subject to elevated respiration rates due to enzyme activity and mould growth that reduce the dry grain and may produce sufficient energy which may be harmful to wheat quality. Grain aeration provides a powerful nonchemical stored grain insect management. Currently, aeration is a suitable and economical device to overcome this problem. The moisture management is vital to prevent spoilage in stored grain. The objective of this study is to investigate the influence of using low relative humidity (RH) aeration on the wheat moisture content. The numerical investigation based on heat and mass balances is developed and used to simulate the evolution of grain temperature and moisture under various air RH in a wheat storage silo. Results show that the dehumidification of blown air had greater potential for decreasing RH of interstitial air and wheat moisture at $30^{\circ }$C temperature and RH of 40%, 50% and 60%.

In hot climatic conditions, increased energy consumption toward cooling has led to the development of evaporative coolers. The performance of evaporative cooler depends on the various material and operating parameters. Type of material selected for cooling pad is the most important factor among them. In this study, various types of cooling pad materials have been discussed based on their potential benefits, influence on the cooling performance like characteristics wettability, porosity, water holding capacity and cost. It is seen that organic- and fiber-based materials have been extensively used, whereas the studies related to materials based on plastics and metals are limited. Ideal material properties to be possessed by a good pad material have been discussed. Prospects and future scope for further research have been identified. Hence, this review paper certainly throws some light on the selection criteria for a potential alternative evaporative cooling pad material that shows the maximum cooling performance and helps achieve sustainable cooling in buildings.

The desiccant cooling mechanism is one of the alternate methods to control the air humidity compared to the conventional air conditioning system. An experimental investigation has been carried out in the current research using a hybrid desiccant in a liquid desiccant dehumidification system. Triethylene glycol (TEG) mixed with different proportions of magnesium chloride (MgCl₂) has been used as the hybrid desiccants. The performance of the dehumidifier was measured using the parameter moisture removal rate and enthalpy effectiveness. The blends of TEG and MgCl₂ gave a better moisture removal rate (MRR) as compared to 100% TEG. The MRR and moisture effectiveness increased with the increasing desiccant flow rate and air flow rate for all of the blend ratios. The blend with 25% MgCl₂ and 75% TEG concentration had relatively high MRR and dehumidification effectiveness. The study reveals that if an optimized blend of TEG and MgCl₂ is used as the desiccant instead of a neat TEG, it will overcome the high viscosity problems of TEG and become one of the promising candidates for sustainable energy sources.

Viral respiratory infections have plagued mankind over its known history. Unfortunately, there has been a lack of meaningful progress in preventing the spread of viral respiratory infections globally. The central dogma appears to be that viruses are the villains. This framing focuses on a viral load balance (VLB) in the air. It follows that physical dilution through various means have been the primary focus of attempts to reduce the spread of infections. The problem of obesity provides a good example of how paradigm blindness can slow down progress in a field. Obesity has been framed as an energy balance disorder that blames overeating and lack of exercise for weight gain. Reframing obesity as a disorder of fat metabolism and storage caused by the quantity and quality of carbohydrates in the diet, referred to as the carbohydrate-insulin model (CIM), opened an alternative line of questioning with a testable hypothesis. Similarly, we postulate an alternative way to frame the spread of viral respiratory infections that would lead to new insights and potentially new ways to prevent infections.

It has long been recognized that viral respiratory infections show a pronounced seasonal variation, referred to as seasonal forging, such that they increase in the winter but decrease or virtually disappear in the summer. In temperate regions, people spend over 90% of their time indoors. This is, therefore, where most respiratory infections are expected to occur. Evidence has been accumulating for decades on the strong correlation between variations in indoor relative humidity (RH) and variations in infection rates. Within a RH Goldilocks zone of 40%-60%, encapsulated viruses like influenza and SARS are optimally inactivated outside the infected host. Below 40% and above 80%, viruses can survive for extended periods in the air or on surfaces. This may explain in part the seasonality of infections as the indoor level of RH in winter is typically about 20% and above 40% in summer in temperate regions. However, the mechanism for the inactivation at midrange RH (in summer) is not well understood. This paper offers a hypothesis that could explain these observations.

We have demonstrated that H₂O₂ and other reactive oxygen species (ROS) are formed spontaneously at the water-air interface of pure water microdroplets. Using only water and a nebulizing gas in the presence of oxygen, we have demonstrated the significant disinfectant potential of pure water microdroplets caused by the activity of H₂O₂ and other ROS. We postulate that spontaneous H₂O₂ and ROS formation in viruses containing exhaled microdroplets have a similar virucidal effect at mid-range RH. The droplet evaporation rate is sufficient to concentrate the solutes and provide enough time for reactions to occur at significantly higher rates than in bulk solutions. The concentration of H₂O₂ has also been shown to be positively correlated to RH. In addition, several other ROS/RNS may be present or formed through interactions with H₂O₂ that may act as even more effective virucide disinfectants to inactivate the virus. Below RH 40% evaporation happens too rapidly for these reactions to make an impact before the droplet is desiccated, and above RH 80% the solutes remain too diluted. Rapid inactivation of viruses at midrange RH may therefore play a greater role in preventing infections than physical dilution of virus load in the air through excessive mechanical ventilation. Similar to obesity, we suggest that a new paradigm that considers virus infectivity outside the host rather than the virus load balance in the air alone could greatly contribute to our understanding of respiratory infections. The proposed new “Relative Humidity Infectivity” RHI paradigm could explain the causal mechanisms underlying seasonal respiratory infections. This can point to better prevention strategies that avoid further distortion of our indoor environment and create conditions within which humans can thrive and be optimally protected. We need more focus on testing the various hypotheses and more data to determine which of the two paradigms will lead us in the right direction or how to use the best of both in an optimal combination. The stakes cannot be higher, and the potential for eradicating future viral respiratory pandemics with nature-based solutions may be right under our noses, literally.

Based on the concept of AAE(apparent activation energy), the warped apparent activation energy (WAAE) is introduced into the reaction engineering model in order to simplify the model. In the paper, the drying dynamic performance of three kinds of dried materials, potato, soap and silica gel, was studied by investigation of the impact of the drying medium (hot-air) relative humidity, which is 8%, 15% and 25%, on the WAAE of dried materials. The studied results show that the WAAE not only reflects the comprehensive effect of water evaporating resistance caused by capillary of porous solid, shrinkage of material surface, but also appears to the diffusivity of vapor molecule in drying medium during drying process.

Atomic force microscopy (AFM) was originally developed for atomic resolution surface topography observations. Nowadays, it is also widely used for nanolithography. AFM-based lithography is an effective method compared to conventional photolithographic processes due to its simplicity, high resolution, and low cost. It can provide nanoscale stage control and the probing tip can be used as a lithographic tool. Therefore, various AFM-based nanoscale fabrication methods have been proposed using electrochemical oxidation, material transfer, mechanical lithography, and thermally induced modifications. This chapter will introduce the detailed processes and applications of AFM-based lithographic techniques.