Design of an Integrated Heat Dissipation Mechanism for a Quad Transmit Receive Module of Array Radar

A radar system requires a number of high-power components operating in a narrow and convection-free environment. This study aims to develop an integrated heat dissipation system that is suitable for the high-power electronic equipment of radar systems. The proposed heat dissipation mechanism integrates a fluid circulation-type cold plate with a quad transmit receive module. The finite element method in the COMSOL fluid–solid coupling heat transfer analysis software was used to analyze the heat dissipation performance of the cold plate in the proposed mechanism. The Taguchi method was adopted to optimize the cold plate design. The simulation and experimental results show that the proposed mechanism can control the temperature equalization and temperature of the system within the specified requirements. The practicality of the proposed mechanism was verified. The findings can serve as a reference for the design of high-power electronic equipment in a heat dissipation system.

Impacts of Dynamical Downscaling on Circulation type Statistics: Potential added Value in the Euro-CORDEX Ensemble

Atmospheric circulation type classification methods were applied to an ensemble of 57 regional climate model simulations from Euro-CORDEX, their 11 boundary models from CMIP5 and the ERA5 reanalysis. We compared frequencies of the different circulation types in the simulations with ERA5 and found that the regional models add value especially in the summer season. We applied three different classification methods (the subjective Grosswettertypes and the two optimisation algorithms SANDRA and distributed k-means clustering) from the cost733class software and found that the results are not particularly sensitive to choice of circulation classification method. There are large differences between models. Simulations based on MIROC-MIROC5 and CNRM-CERFACS-CNRM-CM5 show an over-representation of easterly flow and an under-representation of westerly. The downscaled results retain the large-scale circulation from the global model most days, but especially the regional model IPSL-WRF381P changes the circulation more often, which increases the error relative to ERA5. Simulations based on ICHEC-EC-EARTH and MPI-M-MPI-ESM-LR show consistently smaller errors relative to ERA5 in all seasons. The ensemble spread is largest in the summer and smallest in the winter. Under the future RCP8.5 scenario, more than half of the ensemble shows an increase in frequency of north-easterly flow and decrease in the Central-Eastern European high and south-easterly flow. There is in general a strong agreement in the sign of the change between the regional simulations and the data from the corresponding global model.

Circulation patterns linked to extreme wet and dry conditions in Mozambique, relationship with climatic modes, and changes since 1961

This study investigates circulation types (CTs) in Africa south of the equator that can be associated with extreme wet and dry conditions in Mozambique; the relationship between the CTs and climatic modes in the south Indian Ocean; and changes in the frequency of occurrence of the CTs since 1961. Obliquely rotated principal component analysis applied to sea level pressure field from NCEP-NACR for the 1961-2020 period was used to derive physically interpretable CTs. At the synoptic scale, widespread rainfall in Mozambique was found to be related to widespread cyclonic activity on the Mozambique landmass and in the southwest Indian Ocean, coupled with abundant onshore moisture advection by southeast winds. On average, this circulation type (CT) was found to be significantly related to the positive phase of the Indian Ocean Dipole and the El Niño climatic modes, which both favor anomalous warming of the (western) tropical Indian Ocean. The aforementioned climatic modes equally constrain the annual frequency of occurrence of the CT, possibly due to the anomalous deepening of cyclonic activity in the southwest Indian Ocean during their active periods. Since 1961 the frequency of occurrence and days of persistence of the aforementioned CT has increased, suggesting a possible increase in the vulnerability of the hydroclimate of Mozambique. Extreme dry conditions in Mozambique can be related to widespread anticyclonic activity on the Mozambique landmass and the southwest Indian Ocean, coupled with the weakening of onshore moisture advection.

Minimizing Lost Circulation Non-Productive Time Using Expected Monetary Value and Decision Tree Analysis

Lost circulation and problems related to drilling present a major challenge for the drilling industry. Each year, billions are spent to treat these problems. There is not a single solution to lost circulation because of the complexity and kind of formations susceptible to this issue. Lost circulation treatment data for the Shuaiba formation (induced fractured formation) were gathered from drilled wells in Southern Iraq (over 2000). Treatments have been grouped according to the volume of mud loss as complete, severe, and partial loss remedies. Detailed costs and probabilities calculations were conducted. The costs of three types of loss treatments (partial, severe, and complete) were handled separately since some treatments of severe, and all treatments of complete losses have to be introducing through open end drill pipe (OEDP). Expected monetary value (EMV) and decision tree analysis (DTA) were utilized to choose the optimal mud loss pathway to treat the lost circulation type. In this study, probability and cost were both considered to select the practical and efficient strategy of stopping mud loss. Too many of the remedy scenarios were investigated. The selection of the optimum strategy for every type of loss was based on the lowest EMV and efficiency. Once both conditions were satisfied, the treatment strategies were selected to treat each type of loss. Treatment strategies were provided for complete, severe, and partial losses as flowcharts that can be utilized as a reference in the field to stop or at least mitigate this troublesome problem. The methods used in this paper have the possibility to be adopted and invested to treat mud loss based on historical data of treatments in any formation worldwide.

Performance Improvement Plan of Air Circulation-Type Solar Heat-Storage System Using Ventilated Cavity of Roof

Indoor solar-heating systems that use ventilated roofs have drawn attention in recent years. The effectiveness and efficiency of such air-heating systems vary depending on the design and operation methods. In Japan, by introducing outside air into a ventilated roof cavity and circulating the air indoors, systems that simultaneously obtain ventilation, solar heating, and heat-storage effects have been actively developed. The conventional systems intake a large volume of outside air to increase the solar heat collection effect. However, there is a risk of heat loss and over-drying when a large amount of cold dry air during winter is introduced. In this paper, plans are presented for improving these solar heating and heat-storage effects by preventing over-drying using indoor air circulation via ventilated cavities in the roof and indoor wall. By comparing the results of the proposed system with those of the conventional system via numerical simulation, the heating load is found to be reduced by 50% or more by circulating indoor air to the ventilated roof and storing the heat in the indoor wall. Moreover, an increased relative humidity of approximately 10% was confirmed by reducing the intrusion of the outside air and keeping the moisture indoors.

Variability and changes of drought-relevant circulation types in southern central Europe

<p>The estimation of regional extreme events (heavy precipitation and droughts) in Central Europe under ongoing climate change especially includes an evaluation of the relationship between atmospheric circulation types and regional droughts taking place in the bilateral research project WETRAX+ (WEather Patterns, Cyclone TRAcks, and related precipitation EXtremes). The study area is located in the south of central Europe, including Austria, parts of Germany, Switzerland, and the Czech Republic.</p><p>For a precipitation-conditioned circulation type classification, atmospheric variable fields from gridded daily JRA55 reanalysis data (Japan Meteorological Agency 2018) and gridded daily precipitation data based on 1756 weather stations in the study area (Zentralanstalt für Meteorologie und Geodynamik 2018) were used for the observation period 1961 to 2017. Seven different regional climate model runs of the Euro-Cordex – Initiative and from ReKliEs-De (Regional Climate Projections Ensemble for Germany) as well as three runs of the global climate model ECHAM6 (greenhouse gas scenario RCP 8.5) were used to estimate future changes in two projection periods (2031-2060 and 2071-2100).</p><p>The large-scale atmospheric circulation types have been derived using a non-hierarchical cluster analysis provided in the COST733 Classification Software. The drought-relevant circulation types are determined according to relative frequencies of circulation type days under a particular percentile of precipitation: If at least 20 percent of the circulation type days are below the 20th percentile of precipitation, the circulation type is defined as drought relevant. Drought-relevant circulation types are examined in terms of trends, persistence, changes in monthly occurrence frequencies, and within-type variability. When transferring the circulation types to the climate model data, each single day of the projection period is assigned to the circulation type to whose centroid fields the respective single fields have the smallest Euclidean distance.</p><p>During the observation period, the trend analyses show that the occurrence of drought-relevant circulation types is significantly more often associated with higher temperatures and lower relative humidity. First results of the analysis for the future climate show an increase of central high-pressure areas over Central and Eastern Europe for the months April to September. Anticyclonic weather conditions with a resulting southwesterly flow occur less frequently.</p>

Development of a Real-Time Controlled Bio-Liquor Circulation System for Swine Farms: A Lab-Scale Study

In this study, an attempt was made to develop a real-time control strategy using oxidation–reduction potential (ORP) and pH (mV) time profiles for the efficient operation of bio-liquor circulation system (BCS) in swine farms and its effectiveness in reducing odor emission through improving manure properties in the slurry pit was evaluated. The lab-scale BCS used in this study comprised a bioreactor and a slurry pit. The bioreactor was operated in a sequence of inflow of swine manure → anoxic phase → aerobic phase → circulation to the slurry pit. The improvement in swine manure properties was elucidated by comparing the results of the BCS slurry pit (circulation type, CT) and conventional slurry pit (non-circulation type, NCT). The results revealed that the ORP time profile successfully detected the nitrate knee point (NKP) in the anoxic phase. However, it was less stable in detecting the nitrogen break point (NBP) in the aerobic phase. The pH (mV) time profile showed a more efficient detection of NBP. Compared to the NCT slurry pit, concentrations of ammonium nitrogen (NH4-N) and soluble total organic carbon (STOC) and other analyzed swine manure properties were much lower in the CT slurry pit. In the aspect of odor reduction, around 98.3% of NH3 was removed in the CT slurry pit. The real-time controlled BCS can overcome the drawbacks of fixed time-based BCS operation and therefore can be considered as a useful tool to reduce odor emission from intensive swine farming operations. However, further studies and refinement in control algorithms might be required prior to its large-scale application.

Compound Temperature and Precipitation Events in the Czech Republic: Differences of Stratiform versus Convective Precipitation in Station and Reanalysis Data

Some natural hazards may result from the coincidences of anomalies of different climatic variables. These so-called compound events can cause extreme impacts. This study analyzes compounds of extreme temperature with notable convective and stratiform precipitation in the Czech Republic during 1982–2016. Characteristics of compound events obtained from 11 stations’ data are compared with those from the gridded ERA-Interim reanalysis. We found that notable stratiform precipitation frequently coincides with warm nights and warm days in winter but with cold days in the other seasons. While the winter stratiform precipitation coinciding with warm days and warm nights is linked to anticyclonic, southwest, northwest, and anticyclonic-northwest circulation types, the northeast type is the most crucial circulation type linked to notable stratiform precipitation coinciding with cold days in all seasons except winter. The compound events of notable convective precipitation occur most frequently in summer and they are joined mainly with warm days. These compound events are associated with anticyclonic, cyclonic, and northwest circulation types. Although the number of days with stratiform compound events is larger in ERA-Interim than in the station data, the results are qualitatively comparable. ERA-Interim is, however, not able to reproduce convective compound events obtained from the station data.

Investigation of Danube river plume formation and propagation based on numerical modeling

The relevance of the studied circulation caused by the water river runoff deals with the anthropological impact on the ecological state of the shelf. River waters, entering into the sea, form mesoscale structures in the delta’s area, characterized by low salinity with a high level of suspended matter and dissolved organic matter. Such structures are called “plume” in modern literature. In this case, the inertial motion of the plume is free to form a rounded area or “bulge” like anticyclonic circulation type of flow. The purpose of this work is to investigate the propagation of freshened waters, formed by the river inflow, the formation of the waters hydrological structure regularities, dynamics of the buoyancy current, and thermohaline front formation on the base of numerical modeling. Numerical modeling is used to study the formation of a river plume and downward propagation of buoyancy current on the shelf without taking into account the tides forcing. A three-dimensional σ-coordinate numerical model was used, adapted for the shelf and estuaries. The calculations were carried out for a rectangular box area. The influence of changes in the main parameters of the runoff, the mouth geometry and wind forcing are considered to development of the plume and the alongshore propagation of buoyancy current. The obtained modeling results for the conditions of the Northwestern Black Sea shelf and the Danube discharge are consistent with the estimates of plume characteristics based on the archival hydrological observations data of water temperature and salinity. The results of this work can be used for further study of hydrological processes in the region of river mouths, the peculiarities of the plumes formation and evolution, assessment of the suspended matter, biogenic elements and microplastics transport in the sea and ocean coastal zones.