Sudden Temperature Changes Research Articles

Temperature deformation of frozensoils at sharp change of temperature

The results are described of the study of temperature deformation of different types of frozen soil in the cycles of cooling-heating at sudden change in temperature. The differences in the nature of the temperature deformation at step and one stage temperature change are shown. The dependences are investigated of the temperature deformation of frozen soils on soil type, moisture and total number of cycles of cooling-heating.

Novel control algorithm for MPPT with Boost converters in photovoltaic systems

The great advances in efficiency and performance of photovoltaic modules would not be very useful if they do not work close to their maximum power point (MPP). In this paper a novel Sliding Mode Control (SMC) based algorithm is proposed to be implemented in a DC/DC converter in order to make an autonomous photovoltaic system to work at the MPP. Once that the design of the novel algorithm has been detailed (especially the novel part relative to the current reference signal) and its stability has been demonstrated, its performance has been compared with two of the most commonly used algorithms in this scope, i.e., Perturbation & Observation (P&O) and Incremental Conductance (IC) algorithms, in addition to a PI controller because it is one of the preferred controllers in industrial applications. This comparison has been carried out taking into account both simulated and experimental tests. The first focused on their behavior when sudden changes in irradiance and temperature, while the lasts analyzed them when the load resistance was varying arbitrarily in actual facilities (composed of a photovoltaic module Mitsubishi PV-TD185MF5, a Boost converter, a variable load and a real-time data acquisition card dSPACE DSP1104 used as the interface between the control algorithm implemented in Simulink/Matlab and the real photovoltaic module). After completing tests under different conditions, we found that the proposed SMC based algorithm outperforms the PI controller and the P&O and IC algorithms, especially in experiments carried out using actual facilities.

Provision of straw by a foraging tower \u2013effect on tail biting in weaners and fattening pigs

BackgroundStraw is one of the most effective rooting materials to reduce tail biting in pigs. A so-called foraging-tower (FT) provides only small quantities of straw compatible with liquid manure systems. The focus of the present study was on the effect of providing straw by FT in order to prevent tail biting in tail docked pigs. Four consecutive batches of 160 pigs, randomly divided into a straw (SG) and a control group (CG) were followed up from weaning to slaughter.ResultsTail wounds (Score ≥ 2) were detected in 104 out of 12,032 single observations (SG n = 48; CG n = 56) in 9 pens (SG n = 4/32; CG n = 5/32) mainly focused on the fattening period of batch 2 due to a failure in the ventilation system. No significant differences concerning the distribution of Score ≥ 2 in pens of the SG and CG could be identified. Bite marks (Score 1) were documented in 395 observations at animal level (SG n = 197, CG n = 198) in all batches. In the nursery period, the air velocity significantly increased the chance that at least one pig per pen and week showed a tail lesion score ≥1 (p = 0.024). In the fattening period ammonia concentration was positively associated with tail lesions (p = 0.007).The investigation of blood samples revealed infections with Mycoplasma hyopneumoniae in all batches and a circulation of Porcine Reproductive and Respiratory Syndrome Virus (NA-vaccine strain) and Porcine Circovirus Type 2 in two batches each. The average daily straw consumption was 3.5 g/pig (standard deviation (SD) = 1.1) during the rearing period and 31.9 g/pig (SD = 7.7) during the fattening period.ConclusionDue to the low prevalence of tail biting in all batches the effect of the FT tower could not be evaluated conclusively. The operation of the FT with an average daily straw consumption of 3.5 g/pig (SD = 1.1) during the rearing period and 31.9 g/pig (SD = 7.7) during the fattening period did not affect the weight gain. Exploratory behaviour seems to cause bite marks (score 1), which do not necessarily result in tail biting. The main outbreak of tail biting was probably triggered by a failure of the ventilation system, which resulted in a number of climatic and air quality changes including higher ammonia concentrations and sudden temperature changes.

AQUACULTURE HEALTH MANAGEMENT AND BIOSECURITY PRACTISES IN SOUTH WEST OF BANGLADESH

Bangladesh is now the world fourth largest inland fish producer and more than half of it comes from aquaculture according to 2012 ranking. The shrimp and prawn industry has gained an important place in the national economy and is the third highest foreign income earner. Concomitant with the growth of the shrimp and prawn culture industry has been the recognition of the ever increasing importance of disease, especially those caused by infectious agents. Few studies have aimed to identify the perception of risk and risk management strategies for small scale aquaculture facilities. The aim of this study was to understand existing health management practices in regards to water management practices and salinity in southwest coastal region of Bangladesh. Questionnaires were specifically designed to gather information on shrimp and prawn culture systems and multiple variables relating to disease outbreaks. A total of eight variables related to health management practices throughout production cycle were investigated comprising location of farm from primary source of water, pond preparation technique, water management practices, in-pond nursing of post larvae (PL), source of PL, salinity level, stocking density and bio security practices. The results found that sharing of water source with other farms, non tested PL, high salinity level, shallow pond, lack of in-pond nursing were considered as diseases risk factors for poly-culture farming system. Furthermore, rainy season (June-August) is risk factors for diseases outbreak because sudden change of salinity level and drop temperature due to rain and freshwater upstream flow. However, risk factors are not direct causes of mortality; instead, risk factors contribute to mortality.

Thermal Comfort Conditions at the Platforms of the Athens Metro

The current study aims at the comparison of the field measurements at the platforms of the Athens Metro with those recommended by international standard thermal comfort and to the investigation of the relationship of environmental parameters between platforms and the outdoor space. The levels of air, operative and globe temperature as well as air humidity and air velocity were continuously monitored at the platform space of two stations with different depth and design features in summer. The predicted mean vote (PMV) model and the predicted percentage of dissatisfied (PPD) index were used. The results reveal that the operative temperature at both stations is far from the traditional still-air comfort zones. For the case of elevated air movement of 1.2 ms-1 and considering the occupants have local control of air speed, 20.3% of the values at the station with the greatest depth do not exceed the upper limit. Furthermore, 64% of the variation in air temperature at the platform of the station with the smallest depth is explained by outdoor air temperature, while the corresponding percentage for the station with the greatest depth is 29%. Passengers experience sudden change of air temperature and PMV, especially at the station with the smallest depth, during their transition from the platform to the interior of air-conditioned train carriages and vice versa.

English

Seasonal outbreaks of swine erysipelas have been reported in back yard pig farms in the Phek district of Nagaland, India. The alpha haemolytic isolate of Erysipelothrix rhusiopathiae was recovered on blood agar from the clinical samples. The organisms were confirmed microscopically, biochemical analysis as well as by polymerase chain reaction (PCR) amplification of 16S rRNA gene and sequence analysis. These Nagaland isolates (KT160358, KT160359) were closely related to the type spp. E. rhusiopathiae in phylogenetic analysis and forms the same clad with Chineese isolates of swine and murine origin indicating an epidemiological link. The isolates were found to be most sensitive to oxytetracycline and responded to treatment. Swine erysipelas occurred in Phek district in a season due to sudden change of weather and temperature. Pigs exposed to such predisposing factors probably favoured to propagation of already persisted organisms in pigs. This is the first confirmed case of E. rhusiopathiae infection from the NE states of Nagaland, India. Key words: Swine erysipelas, Erysipelothrix rhusiopathiae, pig, polymerase chain reaction (PCR) Nagaland, India, Oxytetracycline.

Analysis of the potential occurrence features in multicomponent ceramic composites based on the refractory anoxic compounds (part 1)

Formation of the functional zone of multicomponent ceramic composite based on refractory anoxic compounds is the object of research. The disadvantages of this object in the existing operating conditions include high inertia, which shows that the produced functional devices do not affected by sudden changes in temperature peak.Research was conducted at the Institute for Problems in Material Science of Ukraine using industrial powders. The investigated samples were produced by plastic forming on the spindle stall in the form of plates 100×7×6 mm. Carboxymethylcellulose (CMC) in combination with a plasticizer (glycerol or rubber) was used as a binder for this method. Investigated samples of silicon-nitride composites based on SIALONs were obtained by hot pressing of prepared ceramic tapes using the induction method of the mold heating.Research was conducted by the methods: chemical analysis of raw materials and samples, X-ray analysis, electron microscopic analysis, X-ray spectral probe microanalysis and quantitative metallographic analysis of microstructure morphology of the ceramic composites.It was established that the formation of functional areas nonlinear device affect technological factors such as: binder type, temperature, isothermal soaking temperature and composition of the gas environment. Reduction of the isothermal soaking temperature leads to increased non-uniformity of resistance by volume of the functional element with decreasing or exceeding the optimum soaking temperature. Binder, binder composition and gas temperature of the environment significantly affect the anisotropy and dimension of conducting of formed cluster. It is shown that microstructure morphology is formed differently for various binders. It is found that TCR passes through «0» for 13 % concentration of HfC.These research results can be used to establish the correlation between process parameters, electrical conductivity and Seebeck coefficient of the solid layered multicomponent ceramic composites based on refractory anoxic compounds. Based on these studies it becomes possible to manufacture highly efficient thermoelectric converters.

Mechanism of the crack formation and suppression in laser-MAG hybrid welded 30CrMnSiA joints

This paper investigated the crack formation and suppression mechanism in laser-metal active gas (MAG) hybrid welded 30CrMnSiA joints. The cracks were usually found in the weld crater that was located at the end of the weld bead. According to the fracture characteristics, the cracks could be considered as solidification cracks. Shrinkage cavities and intergranular films were found by means of scanning electron microscopy (SEM) observation, confirming the presence of solidification cracks. The energy dispersive spectrometer (EDS) shows severe segregation of impurity elements in the weld metal. The following differential thermal analysis (DTA) shows that there was a sudden change in the differential temperature in the range of 1130°C–1150°C, indicating that the low melting point eutectic inducing solidification cracks was most likely to be FeS-MnS eutectic. Finite element models for heat sources were developed. The tensile test results show that the tensile strength of weld metal reached 40MPa at 1100°C but dropped to about 24MPa at 1150°C, while the calculated highest transverse tensile stress amounted to 430MPa. Therefore, the tensile stress at the end of the weld seam exceeded the tensile strength by approximately 400MPa. By adopting double-layer hybrid welding process, crater cracks were successfully suppressed. The electron backscattered diffraction (EBSD) shows that the microstructure of double-layer hybrid welded joints was notably refined. The tensile stress of the weld metal was reduced and intergranular films were absent.

Migrating zooids allow the dispersal of Fredericella sultana (Bryozoa) to escape from unfavourable conditions and further spreading of Tetracapsuloides bryosalmonae

Fredericella sultana (Bryozoa: Phylactolaemata) is a primary host in the two-host life cycle of the myxozoan parasite Tetracapsuloides bryosalmonae, the etiological agent of Proliferative Kidney Disease (PKD) in salmonids. Overtly infected F. sultana colonies were collected from River Kamp (Lower Austria), following the first PKD outbreak affecting autochthonous brown trout (Salmo trutta) in Austria. Zooids cultured under unfavourable conditions, e.g. hypertrophication or sudden temperature changes, disconnected their funiculus from the bottom of the body wall, contracted their retractor muscle and packed all organs into a pear-shaped capsule. Migrating zooids dislocated from larger dying branches by separating from the degenerating zooecial tube. After attaching to a new substrate, a new colony could grow rapidly, similar to newly hatched zooids from statoblasts. This is the first observation of an adaptive dispersal mechanism undertaken by adult viable bryozoan zooids to escape from colony deterioration upon adverse summer-like conditions. The evidence of migrating zooids for F. sultana colonization of new habitats increases their intrinsic capacity of spreading infective T. bryosalmonae malacospores.

Dynamic mechanical properties and deterioration of red-sandstone subjected to repeated thermal shocks

Rock engineering and stone constructions are always suffering recurrent thermal shock (TS) generated by sudden changes in temperature, and rock mechanical behaviors in projects usually involve responses to stress pulses or impact loads due to the widely existed blasting operation, mechanized construction and seismic oscillation. In this work, physical tests as well as static and dynamic mechanical experiments were carried out on red-sandstone free from and after 10, 20, 30, and 40 artificial TS cycles. TS-induced changes of physico-mechanical properties, including micromorphology, density, porosity, P-wave velocity, uniaxial compressive strength (UCS) and deformation modulus (Ed), illustrated the deterioration of sandstone after different TS cycles. Strengthening effects of strain rate on the dynamic mechanical properties of TS-weathered red-sandstone were analyzed. Considering the strain rate effect, deterioration models of dynamic UCS and Ed were built to predict the dynamic mechanical degradation of porous rock after repeated TS weathering. The model parameters, decay constant (λ) which indicated the mean relative integrity loss by the action of any single TS cycle, and half-life (N1/2) which measured the number of cycles necessary to reduce the integrity to half its value, were both expressed as functions of strain rate.

Emergency treatment and nursing of children with severe pneumonia complicated by heart failure and respiratory failure: 10 case reports

Pneumonia refers to lung inflammation caused by different pathogens or other factors, and is a common pediatric disease occurring in infants and young children. It is closely related to the anatomical and physiological characteristics of infants and young children and is more frequent during winter and spring, or sudden changes in temperature. Pneumonia is a serious disease that poses a threat to children's health and its morbidity and mortality rank first, accounting for 24.5–65.2% of pediatric inpatients. Due to juvenile age, severe illness and rapid changes, children often suffer acute heart failure, respiratory failure and even toxic encephalopathy at the same time. The concurrence in different stages of the process of emergency treatment tends to relapse, which directly places the lives of these children at risk. Severe pneumonia constitutes one of the main causes of infant mortality. In the process of nursing children with severe pneumonia, intensive care was provided, including condition assessment and diagnosis, close observation of disease, keeping the airway unblocked, rational oxygen therapy, prevention and treatment of respiratory and circulatory failure, support of vital organs, complications, and health education. The inflammatory response was proactively controlled, to prevent suffocation and reduce mortality. In summary, positive and effective nursing can promote the rehabilitation of children patients, which can be reinforced with adequate communication with the parents and/or caretakers.

Diseño e implementación de un prototipo electrónico para monitoreo de parámetros físico-químicos en cultivo de tilapia a través de una aplicación móvil

En los estanques de agua dulce para cultivo de tilapia, especialmente en su etapa de engorde, se presenta un alto índice de mortalidad de peces. Debido a lo anterior, fue diseñado e implementado un prototipo electrónico para monitorear los parámetros físico-químicos como temperatura y oxígeno disuelto del agua, con el fin de identificar los momentos críticos del cultivo. Las pruebas en campo se realizaron en la granja piscícola “Pezcomsi”, ubicada en el municipio de Campoalegre, en el departamento del Huila (Colombia). El prototipo cuenta con un sistema de adecuación de las señales para los sensores, las cuales llegan al microprocesador ATMEGA 328P, que realiza el proceso de adquisición y conversión de datos análogos a digitales para su procesamiento y almacenamiento en una memoria microSD. A través del módulo Bluetooth HC-05, estos datos son enviados a la interfaz gráfica soportada en una aplicación móvil, en donde el usuario puede visualizar el comportamiento de las variables en el cultivo. El sistema es alimentado por medio de paneles solares y presenta porcentajes de error bajo comparados con patrones estándar, por lo que se considera una herramienta electrónica de monitoreo confiable. Con este sistema se espera contribuir a la disminución de índices de mortalidad de la tilapia, debido a cambios bruscos de temperatura y oxígeno disuelto que se presentan diariamente en los estanques; además, los resultados encontrados muestran una disminución en la concentración de oxígeno disuelto que podría ser objeto de estudio posterior.

A Thermochromic Superhydrophobic Surface

Highly enhanced solid-state thermochromism is observed in regioregular poly(3-hexylthiophene), P3HT, when deposited on a superhydrophobic polymer-SiO2 nanocomposite coating. The conformal P3HT coating on the nanocomposite surface does not alter or reduce superhydrophicity while maintaining its reversible enhanced thermochromism. The polymeric matrix of the superhydrophobic surface is comprised of a blend of poly(vinylidene fluoride-co-hexafluoropropylene) copolymer and an acrylic adhesive. Based on detailed X-ray diffraction measurements, this long-lasting, repeatable and hysteresis-free thermochromic effect is attributed to the enhancement of the Bragg peak associated with the d-spacing of interchain directional packing (100) which remains unaltered during several heating-cooling cycles. We propose that the superhydrophobic surface confines π–π interchain stacking in P3HT with uniform d-spacing into its nanostructured texture resulting in better packing and reduction in face-on orientation. The rapid response of the system to sudden temperature changes is also demonstrated by water droplet impact and bounce back on heated surfaces. This effect can be exploited for embedded thin film temperature sensors for metal coatings.

Survival Rate and Hematological Responses with Temperature Changes of Red Spotted Grouper, Epinephelus akaara in South Korea.

The effect of sudden changes of water temperature (WT) on the survival rate and physiological responses of the red spotted grouper (Epinephelus akaara) were examined by manipulating WT control system for 9 days. Experimental condition was divided in two different regimes at low (from 10°C to 4°C, decreased 1℃/d) and high (from 28°C to 34°C, increased 1°C/d) WT. Survival rate of experimental fishes were observed, and determined the changes of hematological characteristics by analyzing plasma levels of cortisol, glucose, total protein, and electrolytes (Na+, Cl–, K+). No mortality was observed until low WT 6°C (144 h) and high WT 32°C (96 h), and 100% mortality was observed at low WT 4°C (216 h) and high WT 35°C (171 h). Plasma levels of cortisol and glucose increased rapidly as decreasing WT, and the loss of swimming ability and respiration response was observed at low WT 7°C and high WT 34°C conditions.

Influence of the microstructure on the thermal shock behavior of cemented carbides

The influence of single and repetitive sudden changes of temperature on the mechanical integrity of cemented carbides was investigated as a function of their microstructure. Thermal shock resistance was assessed by testing the residual flexural strength of hardmetal beams after being subjected to thermal shock by water quenching. Results indicate that hard cemented carbides tend to exhibit a superior resistance to the nucleation of thermal shock damage but a lower resistance to the propagation of this damage mechanism than tough grades, and vice versa. These trends are in agreement with those expected from the evaluation of the thermal shock Hasselman’s parameters. The evidenced strength loss after thermal shock may be related to the subcritical growth of intrinsic flaws driven by localized microcracking surrounding them. Results also point out on Ni-base hardmetals to exhibit a slightly higher resistance to abrupt changes of temperature than Co-base ones.

Event water detection in tile drainage runoff using stable isotopes and a water temperature in small agricultural catchment in Bohemian-Moravian Highlands, Czech Republic

The tile drainage runoff composition during rainfall–runoff (R–R) events was examined in a small agricultural catchment Dehtaře (Bohemian-Moravian Highlands, Czech Republic). Drainage systems in this region of crystalline bedrock are typically built in slopes and they have complicated runoff generation. For runoff separation, analysis of stable isotopes 18O and 2H was used and compared to sudden changes in drainage water temperature. The analysis of 18 hydrographs showed that the drainage runoff was composed of 1–58 % event water during summer events, with a maximum temporary share of 11 and 88 %. During winter events, the pre-event water significantly dominated. In all cases when event water was detected in the drainage runoff, a rapid change in the drainage water temperature was observed as well. Its values during R–R events converged toward the temperature of the precipitation, which was very similar to that of the air (R 2 = 0.98 %). As the magnitude of the water temperature change was proportional to the event water portion in the drainage runoff (R 2 = 0.91), it is possible to state that a sudden change in drainage water temperature indicates the presence of event water in the drainage runoff and it is possible to use water temperature successfully to separate the runoff components.

Influence of Temperature on the Nanoadhesion of a Methyl-Terminated Thiol Monolayer: A New Insight with High-Rate Dynamic Force Spectroscopy.

Alkanethiols form stable, homogeneous, and well-organized self-assembled monolayers and can be used as lubricants in micro- and nanodevices when sufficiently hydrophobic and resistant to sudden temperature changes. In this paper, we demonstrate a new analysis method which provides a deep physical insight into adhesive interactions and their temperature dependencies at the single molecule level. We have focused on the adhesion between a silicon nitride tip and a 1-decanethiol self-assembled monolayer in the temperature range from 25 to 85 °C. We performed dynamic force spectroscopy measurements and applied theoretical models of adhesive-mechanical interactions and thermally activated unbinding to obtain detailed information on the adhesive interactions. The parameters of the interaction potential describing a single adhesive bond were calculated, and their temperature dependence was discussed. Although the changes of the adhesion force versus temperature are significant and nonmonotonic, the energy of the activation barrier of a single adhesive bond appears temperature independent. We attribute observed changes in the position of the activation barrier to the interplay between the rupture and rebinding of adhesive bonds, as well as to thermal reorganization, in particular the change of the tilt angle of thiol molecules in the self-assembled monolayer.

Temperature-driven transient charge and heat currents in nanoscale conductors

We analyze the short-time behavior of the heat and charge currents through nanoscale conductors exposed to a temperature gradient. To this end, we employ Luttinger's thermomechanical potential to simulate a sudden change of temperature at one end of the conductor. We find that the direction of the charge current through an impurity is initially opposite to the direction of the charge current in the steady-state limit. Furthermore, we investigate the transient propagation of energy and particle density driven by a temperature variation through a conducting nanowire. Interestingly, we find that the velocity of the wavefronts of, both, the particle and the energy wave have the same constant value, insensitive to changes in the average electronic density. In the steady-state regime, we find that, at low temperatures, the local temperature and potential, as measured by a floating probe lead, exhibit characteristic oscillations due to quantum interference, with a periodicity that corresponds to half the Fermi wavelength of the electrons.

Hatching plasticity in the tropical gastropod Nerita scabricosta

AbstractHatching plasticity has been documented in diverse terrestrial and freshwater taxa, but in few marine invertebrates. Anecdotal observations over the last 80 years have suggested that intertidal neritid snails may produce encapsulated embryos able to significantly delay hatching. The cause for delays and the cues that trigger hatching are unknown, but temperature, salinity, and wave action have been suggested to play a role. We followed individual egg capsules of Nerita scabricosta in 16 tide pools to document the variation in natural time to hatching and to determine if large delays in hatching occur in the field. Hatching occurred after about 30 d and varied significantly among tide pools in the field. Average time to hatching in each pool was not correlated with presence of potential predators, temperature, salinity, or pool size. We also compared hatching time between egg capsules in the field to those kept in the laboratory at a constant temperature in motionless water, and to those kept in the laboratory with sudden daily water motion and temperature changes. There was no significant difference in the hatching rate between the two laboratory treatments, but capsules took, on average, twice as long to hatch in the laboratory as in the field. Observations of developing embryos showed that embryos in the field develop slowly and continuously until hatching, but embryos in the laboratory reach the hatching stage during the first month of development and remain in stasis after that. Instances of hatching plasticity in benthic marine invertebrates, like the one in N. scabricosta, could greatly enhance our ability to investigate the costs and benefits of benthic versus planktonic development, a long‐standing area of interest for invertebrate larval biologists.

The effects of daily bathing on symptoms of patients with bronchial asthma.

BackgroundThe influence of bathing in asthma patients is not yet fully known.ObjectiveWe conducted an observational study to investigate changes in symptoms and their degree by bathing in asthmatic patients.MethodsA questionnaire focusing on ever experienced bathing-induced symptom changes and their degree, as well as contributing factors, was designed and administered to asthmatic patients in the outpatient department of our institute between January 2012 and November 2013.ResultsTwo hundred fifteen cases were recruited. In 60 cases (27.9%), asthmatic symptoms appeared, including 20 cases of chest discomfort (33.3%), 19 cases of cough (31.7%), and 21 cases of wheezing (35.0%). The triggering factors included vapor inhalation (32 cases, 53.3%), hydrostatic pressure on the thorax due to body immersion in the bathtub (26 cases, 43.3%), and sudden change of air temperature (16 cases, 26.7%). Thirty-eight cases (17.7%) experienced improvement in active asthmatic symptoms by bathing. Vapor inhalation was the most common contributing factor (34 cases, 89.5%), followed by warming of the whole body (13 cases, 34.2%). There was no relationship between asthma severity and the appearance of bathing-induced symptoms or improvement of active asthmatic symptoms by bathing.ConclusionThe effects of bathing in asthmatic patients widely differed from patient to patient and their etiology includes several factors. For those who suffer from bathing-induced asthma symptoms, preventive methods, such as premedication with bronchodilators before bathing, should be established. This study is registered in the University Hospital Medical Information Network (UMIN) clinical trials registry in Japan with the registration number UMIN000015641.