Study on the hygroscopicity of PET foam sandwich structure

Polyethylene terephthalate (PET) foam sandwich structure is widely used in the fields of construction, aerospace and shipbuilding. We have conducted research on its hygroscopic phenomenon. Take different sizes of GFRP panels, PET foam and PET foam sandwich structure for moisture absorption tests, analyze the data on the basis of the classic Fick’s law of diffusion to obtain the moisture absorption curves of each sample. And get the diffusion coefficient of the specimen. Then, we use the multi-physics software COMSOL to model and analyze the moisture absorption properties of the specified samples. The moisture absorption curve obtained by theoretical calculation was compared with the experimental moisture absorption curve, and the results showed that the two Good agreement. Tests have proved that the moisture absorption performance of PET foam is much greater than that of GFRP panel material, and the relative moisture absorption is related to the specific surface area of the sample. In the PET foam sandwich structure, the GFRP panel can effectively inhibit the hygroscopicity of the PET foam and has an excellent protective effect on the PET foam.

A numerical simulation of air flow in the human respiratory system for various environmental conditions

The functions of the nasal cavity are very important for maintaining the internal environment of the lungs since the inner walls of the nasal cavity control the temperature and saturation of the inhaled air with water vapor until the nasopharynx is reached. In this paper, three-dimensional computational studies of airflow transport in the models of the nasal cavity were carried out for the usual inspiratory velocity in various environmental conditions. Three-dimensional numerical results are compared with experimental data and calculations of other authors. Numerical results show that during normal breathing, the human nose copes with heat and relative moisture metabolism in order to balance the intra-alveolar conditions. It is also shown in this paper that a normal nose can maintain balance even in extreme conditions, for example, in cold and hot weather. The nasal cavity accelerates heat transfer by narrowing the air passages and swirls from the nasal concha walls of the inner cavity.

FABRICATION OF GRANULAR HUMIDITY INDICATOR

This work presents the fabrication of the granular humidity indicator for the monitor of the relative moisture in the outdoor environment or in the enclosed areas such as bags, containers, enclosed rooms, boxes which are used for the storage of the weapons and military equipment, food preservation, seed storage in agriculture, controlling fermentation process as well as the plants growing process, etc. Moisture indicator was fabricated from cobalt chloride, desiccant, color-stabilizing agents, and silica gel particles. The obtained indicator can measure the relative humidity in the range of 30 to 70 based on the color changing from the indicator.

Optimal rearing medium for the population growth of the predatory mite, Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae)

Background The successful rearing of predators or parasitoids is one of the most important elements in biological control programs. The dried fruit mite, Carpoglyphus lactis (L.), can be used as an alternative prey for the phytoseiid predatory mite, Amblyseius swirs0kii (Athias-Henriot). Main body This study aimed to evaluate the suitability of 3 different diets for C. lactis when rearing A. swirskii: brown sugar, baker’s yeast, and the mixture of brown sugar and baker’s yeast along with 3 initial predator:prey ratios (1:7, 1:12, and 1:20). After 30 days, both the baker’s yeast and the mixture of brown sugar + baker’s yeast diets resulted in the highest predator densities (40.5 times increase at an initial predator:prey ratio of 1:20, with the baker’s yeast diet), whereas the mixture diet produced the highest density of prey. The brown sugar resulted in the lowest number of predator and prey mites. This may be due to lower feeding and predation rates of the prey and the predator mites on the brown sugar medium since its relative moisture content and adhesiveness inhibits mite movement. The final predator:prey ratio was also highest on the baker’s yeast diet. Conclusions This study demonstrated that the population growth of A. swirskii was the highest when C. lactis was reared on baker’s yeast.

Study on the Mitigative Effect of Controlled Permeable Formwork (CPF) Liner on Early-Age Shrinkage of Box-Girder Concrete

Because of its high binder content and severe construction environment, early-age cracking is one of the most important threats to concrete used in continuous box-girder bridge structures. In this study, controlled permeable formwork (CPF) liner was used to mitigate the early-age shrinkage and reduce the early-age cracking risk of box-girder concrete. Early-age shrinkage was measured by a noncontact method and started at 30 min after adding mix water until 7 d. Internal relative moisture content and pore distribution tests were also carried out to reveal the working mechanism of CPF liner. The results show that covering the concrete surface with CPF liner decreased early-age shrinkage significantly. Under the temperature of 20°C and the relative humidity of 60%, two-surface-covering and three-surface-covering CPF liner on concrete decreased the shrinkage by 44% and 48%, respectively, at 7 d compared with concrete without CPF liner covered on it. The main reason is that CPF liner enhanced the internal relative moisture content and resulted in better performance of the surface concrete.

The Study of Corn Cobs and Gypsum AddingIn Some Physical Characters and Organic Matterof Cracking Soils from Middle of Iraq

In order to investigate the role corn cobs and gypsum in some physical charactersand organic matter ofclayey cracks and their properties. Seven soils sites (Afak, Al-Diwaniyah, Al-Taleea, Babel, Agriculture college, Al-Wahda and Al-Raid project) There are three types of treatments as follows: - Corn cobs was applied in four levels (0 . 10 . 20 and 40) g.kg-1 - Gypsum (calcium sulfate) applied in four levels (0 , 5 , 7.5 and 10) g.kg-1. - Treatments of interaction between corn cobs and gypsum. Corn cobs , gypsum and their interaction were applied in same levels above. In this experiment , 2 kg of each studied soil were treated with same levels of corn cobs and gypsum above and incubated at 30 + 2 °C for 90 days and 80% relative moisture content at 33 kpa. The results were summarized as :Soil aggregate stability (MWD) and organic matter values were increased , while modules of rupture and (COLE) values were decreased , with increasing of gypsum and corn cobs applying. Also, results showed that the decreasing of (COLE) values were depending on the clay content and interaction treatments , between corn cobs and gypsum. The decreasing of (COLE) values were the highest in the clayey cracks disappeared treatments.

Role of Gypsum and Corn Cobs in Linkage of Peds in Cracking Soils

To study role of gypsum and corn cobs in linkage of fractions in cracking soils. Three soils (Al-Diwaniya , Al-Wihda and college of Agriculture / Abu Ghraib) were chosen for this study . They were treated with two levels of gypsum (0.5 and 1) % with one level (4%) of corncobs . In this experiment , 2 kg of each studied soil were treated with same levels of corn cobs and gypsum above and incubated at 30 + 2 °C for 90 days and 80% relative moisture content at 33 kpa. And then the soils were sieved with 1 mm sieve to measured the x-ray diffractions . The results showed : The intensity of clay minerals peaks which treated with gypsum and corn cobs were decreased comparing with control sample. We believed that the gypsum should be facculated on clay minerals surfaces and mask them to appear clearly , and suggested that the gypsum was played an important role in conjugated of soil particles. Results of X-ray diffractions showed that there was no evidence of interaction between organic matter (corn cobs) and clay mineral inter layers.

Kinetic aspects of a dried thin layer carrot in a heat pump dryer

This article presents a mathematical model for drying thin layer carrot slices (Daucus carota) using a heat pump dryer (HPD). To select the equation that best describes the drying curve, 10 semi-theoretical and/or empirical models were evaluated. The parameters were determined using the Sigma-Plot® program, and their goodness of fit was compared using the correlation coefficient, R²; Chi-squared, <span style="font-family: symbol;">C</span>²; standard error of the estimate (SEE) and root mean square error (RMSE). Additionally, the effect of the relative moisture, sample thickness and air velocity on the effective diffusivity of the process was evaluated using a response surface tool. Although all the models correctly fit the experimental data, based on the statistical tests, the Wang-Singh model was selected as the best.