Impact of a power plant cooling system on copepod and meroplankton survival (Bahía Blanca estuary, Argentina)

The impact of a power plant cooling system in the Bahía Blanca estuary (Argentina) on the survival of target zooplanktonic organisms (copepods and crustacean larvae) and on overall mesozooplankton abundance was evaluated over time. Mortality rates were calculated for juveniles and adults of four key species in the estuary: Acartia tonsa Dana, 1849 and Eurytemora americana Williams, 1906 (native and invading copepods), and larvae of the crab Chasmagnathus granulata Dana, 1851 and the invading cirriped Balanus glandula Darwin, 1854. Mean total mortality values were up to four times higher at the water discharge site than at intake, though for all four species, significant differences were only registered in post-capture mortality. The findings show no evidence of greater larval sensitivity. As expected, the sharpest decrease in overall mesozooplankton abundance was found in areas close to heated water discharge.

Energy evaluation of an evaporative cooling system using water driven ejector

The search for efficient and accessible cooling systems has increased worldwide. This study aims to build and evaluate an evaporative cooling system using a water driven ejector, allowing it to be installed in places with plenty of water. The system was investigated varying the flow rate and temperature of the circulating water, temperature of the replacement water, and coefficient of performance. The best vacuum obtained was 8.5 kPa at nominal operating conditions of 4.1 ± 0.1 m³/h and 5 ± 0.5 ºC for the circulating water reaching the temperature of 9.7 ± 0.5 ºC. The pulse-like disturbance generated by replacing the cooling water at different periods of times did not result in significant affect vacuum destabilization and the temperature rise in the cooling tank. The coefficient of performance of the system at the highest thermal power of 92.27 W was 0.077, which was underestimated due to possible problems related to pump efficiency. The system evaluated under the conditions proposed can be very efficient for cooling fluids at higher temperatures, and it can be complementary to main refrigeration systems.

Physiological indicators of stress in gestating sows under different cooling systems

The objective of this work was to determine physiological stress markers, neutrophil:lymphocyte ratio (N/L) and corticoid concentrations, in gestating sows under different cooling systems. A sprinkling cooling system (SS) and a system based on fan-assisted evaporative cellulose pad (PS) were used. SS showed higher N/L ratio (1.095) than PS (0.850). Corticoid concentrations showed high variability. Corticosteroids are more efficient short-term stress indicators while N/L ratio is a good medium and long-term stress indicator. According to N/L ratio, gestating sows under PS benefit from a higher level of welfare.

System for studies of control strategies applied in the refrigerated chambers

The process of cold storage chambers contributes largely to the quality and longevity of stored products. In recent years, it has been intensified the study of control strategies in order to decrease the temperature change inside the storage chamber and to reduce the electric power consumption. This study has developed a system for data acquisition and process control, in LabVIEW language, to be applied in the cooling system of a refrigerating chamber of 30m³. The use of instrumentation and the application developed fostered the development of scientific experiments, which aimed to study the dynamic behavior of the refrigeration system, compare the performance of control strategies and the heat engine, even due to the controlled temperature, or to the electricity consumption. This system tested the strategies for on-off control, PID and fuzzy. Regarding power consumption, the fuzzy controller showed the best result, saving 10% when compared with other tested strategies.

The impact of evaporative cooling on the thermoregulation and sensible heat loss of sows during farrowing

Pigs are more sensitive to high environmental temperatures explained by the inability of sweating and panting properly when compared to other species of farmed livestock. The evaporative cooling system might favor the thermal comfort of animals during exposure to extreme environmental heat and reduce the harmful effects of heat stress. The purpose of this study was to assess the sensible heat loss and thermoregulation parameters from lactating sows during summer submitted to two different acclimatization systems: natural and evaporative cooling. The experiment was carried out in a commercial farm with 72 lactating sows. The ambient variables (temperature, relative humidity and air velocity) and sows physiological parameters (rectal temperature, surface temperature and respiratory rate) were monitored and then the sensible heat loss at 21days lactation was calculated. The results of rectal temperature did not differ between treatments. However, the evaporative cooling led to a significant reduction in surface temperature and respiratory rate and a significant increase in the sow's sensible heat loss. It was concluded that the use of evaporative cooling system was essential to increase sensible heat loss; thus, it should reduce the negative effects of heat on the sows' thermoregulation during summer.

Tratamento de águas de refrigeração com peróxido de hidrogênio

Hydrogen peroxide and chlorine are compared as possible disinfectants for water-cooling circuits. To this purpose, samples taken from the cooling system of a steel making plant were treated (at 25ºC and pH values of 5.5 and 8.5) with varying amounts of the two oxidizing agents (0.0 mg/L, 2.0 mg/L and 6.0 mg/L). The results were evaluated through bacterial counting and measurement of corrosion rates upon AISI1020 carbon steel coupons. Bacterial removal and corrosion effects proved to be similar and satisfactory for both reagents.

Benefits of automated acclimatization during the pre-milking phase of lactating girolando cows

The aim of this paper was to evaluate the automated acclimatization effects during pre-milking of cows on thermal conditioning, physiology, milk production and cost-benefit of the automated adiabatic evaporative cooling system (AECS). The treatments 20; 30; 40 min and control consisted of exposure time of pre-milking cows to the automated AECS. Sixteen cows were used with an average daily milk yield of 19 kg, distributed in a 4 x 4 Latin square design. The Tukey's test (P<0.05) was used to compare the means. The environmental variables, dry bulb temperature (DBT, ºC) and relative humidity (RH, %), were recorded every minute, which allowed the determination of the system efficiency through the Temperature and Humidity Index (THI). The respiratory rate (RR), rectal temperature (RT) and temperature of the coat (TC) were measured before and after the acclimatization. The 40 min treatment kept the environmental variables and the comfort indexes within recommended limits. The physiological variables (RR, RT and TC) were lower in the 40 min treatment and reflected positively on milk production, which increased 3.66% compared to the control treatment. The system was profitable, having a 43 days return on investment and a monthly revenue increase of R$ 1,992.67.

Low cost driver device for microclimate maintenance in the pre-milking of dairy cattle

Due to the importance of the environment on animal production and thus environmental control, the study aims to build a system for monitoring and control the meteorological variables, temperature and relative humidity, low cost, which can be associated with an evaporative cooling system (ECS). The system development included all the stages of assembly, test and laboratory calibration, and later the validation of the equipment carried in the field. The validation step showed results which allowed concluding that the system can be safely used in the monitoring of these variables. The controller was efficient in management of the microclimate in the waiting corral and allowed the maintenance of the air temperature within the comfort range for dairy cattle in pre-milking with averaged 25.09 ºC during the afternoon. The equipment showed the lower cost (R$ 325.76) when compared to other middle market (R$ 450.00).

Control system for forced-air cooling of horticultural products

This work is a study of the implementation of a classical controller using a tuning method referred to as IMC (Internal Model Control) and aimed at the reduction of electrical energy consumption by the appropriate relation between energy consumption and the cooling time with forced air. The supervisory system installed was able to manipulate the variable of frequency of the signal power of the exhaust fan engine (forced air module), to accelerate or decelerate the loss of heat from the product to be cooled by airflow variation that passes through the mass of the produce. The results demonstrated a reduction in energy consumption from 64% and an increase of only 8% in the cooling time to the system using PI/IMC (Proportional - Integral with IMC) tuning method compared with the system in its operating nominal condition. This PI/IMC control may be implemented directly in a frequency converter, without the need to purchase a computer or PLC (programmable logic controller) to run the dedicated application, increasing its economical viability.

Climate governance in an international system under conservative hegemony: the role of major powers

In the last five years, climate change has been established as a central civilizational driver of our time. As a result of this development, the most diversified social processes - as well as the fields of science which study them - have had their dynamics altered. In International Relations, this double challenge could be explained as follows: 1) in empirical terms, climate change imposes a deepening of cooperation levels on the international community, considering the global common character of the atmosphere; and 2) to International Relations as a discipline, climate change demands from the scientific community a conceptual review of the categories designed to approach the development of global climate governance. The goal of this article is to discuss in both conceptual and empirical terms the structure of global climate change governance, through an exploratory research, aiming at identifying the key elements that allow understanding its dynamics. To do so, we rely on the concept of climate powers. This discussion is grounded in the following framework: we now live in an international system under conservative hegemony that is unable to properly respond to the problems of interdependence, among which - and mainly -, the climate issue.

Between system maker and privileges taker: the role of China in the Greater Mekong Sub-region

Utilizing China's leadership projects in the Great Mekong Sub-Region (GMS) as a case study, this paper aims to investigate whether China qualifies as an international leader. This work argues that its geographic position and economic rise allow China to be a "system maker and privilege taker," which is a dual role forming in economic-political relations in the GMS in the last ten years. China is among major driving forces to set up an economic zone in GMS. Growing Chinese regional power is intimately related to the creation of various hubs connecting regional transportation, communication and energy systems that foster the economic development of this region. However, China also proves dark sides of rising powers which take advantage of their privileges to gain benefits. As a "system maker" with its own position and capability, China has notably benefited from building hydropower systems. More importantly, while China is pursuing its benefits and privileges, its hydropower projects have caused some negative effects for the ecosystem in the region. The inflation of dam constructions in both China and GMS countries is raising concerns about using natural resources of the Mekong River. Our concluding part addresses the pressing need to start a serious discussion on the balance between national interests and regional solidarity within the formulation of Chinese foreign policy in GMS.

Environmental issues and international relations, a new global (dis)order - the role of International Relations in promoting a concerted international system

Is it possible to talk about the rise of a new global (dis)order founded on the challenges posed by environmental issues? Through the review of the state of the art on the subject, this article analyzes the growing importance of the environment, and natural resources in particular, in international relations; and aims to raise awareness among International Relations scholars to the potential positive impact of the development of the discipline in integration with global environmental change studies.

Evaluation of respiratory parameters in minimally processed lettuce grown under organic or conventional system

The increased preference for minimally processed vegetables has been attributed to the health benefits associated with fresh produce and the demand for ready-to-eat salads. In this paper, lettuce (Lactuca sativa L.) was evaluated for the effects of different cropping systems on the respiratory properties. Lettuce was packaged in low density polyethylene bags and stored in a refrigerator at 4 ºC. The concentration of carbon dioxide and oxygen inside the package was monitored during the storage at zero, three, six, eight, ten and twelve days by gas chromatography. Dry matter variation was measured gravimetrically up to day fourteen of storage. Values of respiratory rate for conventional lettuce increased from day 1 to 3 and remained low, while respiratory rate of the organic lettuce increased three-fold up to day 8, stabilizing at a high level. Variation in dry matter during storage also resulted from differences between the two cultivation systems. The highest content of dry matter was achieved by organic lettuce.

Lime and fertilizer recommendation system for coconut trees

Fertilizer recommendation to most agricultural crops is based on response curves. Such curves are constructed from field experimental data, obtained for a particular condition and may not be reliable to be applied to other regions. The aim of this study was to develop a Lime and Fertilizer Recommendation System for Coconut Crop based on the nutritional balance. The System considers the expected productivity and plant nutrient use efficiency to estimate nutrient demand, and effective rooting layer, soil nutrient availability, as well as any other nutrient input to estimate the nutrient supply. Comparing the nutrient demand with the nutrient supply the System defines the nutrient balance. If the balance for a given nutrient is negative, lime and, or, fertilization is recommended. On the other hand, if the balance is positive, no lime or fertilizer is needed. For coconut trees, the fertilization regime is divided in three stages: fertilization at the planting spot, band fertilization and fertilization at the production phase. The data set for the development of the System for coconut trees was obtained from the literature. The recommendations generated by the System were compared to those derived from recommendation tables used for coconut crop in Brazil. The main differences between the two procedures were for the P rate applied in the planting hole, which was higher in the proposed System because the tables do not pay heed to the pit volume, whereas the N and K rates were lower. The crop demand for K is very high, and the rates recommended by the System are superior to the table recommendations for the formation and initial production stage. The fertilizer recommendations by the System are higher for the phase of coconut tree growth as compared to the production phase, because greater amount of biomass is produced in the first phase.