500 research outputs found
Exploring the boundaries of Solar Home Systems (SHS) for off-grid electrification: Optimal SHS sizing for the multi-tier framework for household electricity access
No full textWith almost 1.1 billion people lacking access to electricity, solar-based off-grid products like Solar Home Systems (SHS) have become a promising solution to provide basic electricity needs in un(der)-electrified regions. Therefore, optimal system sizing is a vital task as both oversizing and undersizing a system can be detrimental to system cost and power availability, respectively. This paper presents an optimal SHS sizing methodology that minimizes the loss of load probability (LLP), excess energy dump, and battery size while maximizing the battery lifetime. A genetic algorithm-based multi-objective optimization approach is utilized to evaluate the optimal SHS sizes. The potential for SHS to cater to every tier of the Multi-tier framework (MTF) for measuring household electricity access is examined. The optimal system sizes for standalone SHS are found for different LLP thresholds. Results show that beyond tier 2, the present day SHS sizing needs to be expanded significantly to meet the load demand. Additionally, it is deemed untenable to meet the electricity needs of the higher tiers of MTF purely through standalone SHS without compromising one or more of the system metrics. A way forward is proposed to take the SHS concept all the way up the energy ladder such that load demand can also be satisfied at tier 4 and 5 levels.DC systems, Energy conversion & StorageElectrical Sustainable Energ
Component method for bolted SHS end plate splice joints loaded in tension
No full textBolted end plate connections are traditional solutions for splice joints with square hollow sections (SHS). A cover plate could be used on one side or two adjacent sides of SHS where the end plate is flushed, resulting in two types of asymmetric splice joints. The advantage of the asymmetric joints is that no space is required between the façade panel and the member surface whilst the easy assembly feature remains. The component method is used to design the bolted end plate connection, as stipulated in prEN 1993–1–8. However, the design rule is only available for connections with open cross-sections. In this paper, a modified component method for predicting the tensile resistance (end plate fails with failure mode 1 according to prEN 1993–1–8) and stiffness of the asymmetric bolted SHS end plate splice joints is proposed. First, a parametric study is carried out to develop the component method for the traditional symmetric bolted SHS end plate splices based on the validated finite element (FE) model. Next, a simplified two-dimensional FE model is employed to evaluate the effect of the asymmetric feature on the stiffness of the joint. Finally, a parametric study is carried out on two types of asymmetric joints to validate the interaction model of individual components. The resistance and stiffness of the asymmetric end plate splice joints are well predicted using the modified component method.Steel & Composite Structure
Evaluating Temperature Impact on Solar Home Systems (SHS): From the components to the systems level
No full textAccess to electricity still lacks for a fifth of the world's population. Most of the areas are in the remote rural location. Due to the off-grid location, policies, and other social factors, the grid expansion in these areas is not economically viable. Installing Solar Home Systems (SHS) is considered to be a promising immediate solution, given that most of these areas are in the tropical region where it has the highest sun-hours in the world. SHS consists of PV modules for the energy generation, batteries for the energy storage, converters for the energy conversion, and load appliances for the energy consumption. However, its high ambient temperature can potentially harm the SHS in decreasing the performance and shortening the lifetime. The lower performance and lifetime can directly translate to have high capital expenses. Therefore a precise quantification of the performance and the lifetime is essential to all the stakeholders.This thesis aims to evaluate and quantify the influence of temperature on the performance and the lifetime of SHS. To achieve the research goal, an integrated SHS model is proposed by considering the performance and the aging behavior of both PV modules and the batteries. Two different battery technologies: Li-ion and Lead-acid are involved in the evaluation. Moreover, the analysis was conducted for Sumba Island, Indonesia since it has great solar potential and also the potential market for the SHS. Furthermore, this work presents a comprehensive investigation of temperature impact from the PV module and battery component level to the system level.Initial system design has been performed in which it requires a 330 Wp PV module, with a tilt and azimuth angle of 11 degrees and 6 degrees respectively, and 960 Wh of batteries to achieve the LLP of 9.5%. The simulation result of the PV component showed clearly that the PV energy yield reduces due to the higher ambient temperature is used. As for the battery, there is a converse behavior concerning the temperature impact in which an increase in temperature gives a positive effect on the capacity and internal resistance in the short term. However, in the long run, it has a severe aging rate.By combining PV module and battery element in an integrated SHS model, it is shown that it achieves to have a 7.4% lower LLP compared to the initial sizing. However, as the aging plays a part, the LLP increases exponentially over the years and can achieve almost doubled the initial LLP. As the ambient temperature increases, it brings negative impacts for the SHS in terms of the performance and the lifetime. It results to have even higher LLP. A decreasing trend of battery lifetime is observed as the ambient temperature increases. Furthermore, it is seen that the system lifetime is limited by the battery lifetime
Position in Croatian countries after entrance in the Kingdom of SHS
No full textPredmet rada je ulazak hrvatskih zemalja u Kraljevstvo SHS te stanje u njima u prvim godinama postojanja Kraljevstva/Kraljevine SHS. Na temelju priložene literature autor iznosi nekoliko teza. Prva jest da je ujedinjenje Države SHS s Kraljevinom Srbijom provedeno na nepovoljan način za hrvatske zemlje. U nastavku rada autor obrađuje proces formiranja vlasti te borbu hrvatskih političkih stranaka za poboljšanje prava hrvatskog naroda i političku ravnopravnost. Zatim opisuje društveno-politički život hrvatskih zemalja tada te argumentira loš odnos vlasti prema hrvatskom narodu u gospodarskim, vjerskim i kulturnim pitanjima. Na kraju rada autor donosi zaključnu tezu da borba hrvatskih političara za preuređenje države na načelu ravnopravnosti svih njezin sastavnih dijelova nije uspjela, štoviše, završava tragično te se kod određenih hrvatskih političara u emigraciji pojavljuje ideja revolucionarne borbe za rušenje Kraljevstva SHS/Kraljevine Jugoslavije te nastanak samostalne hrvatske države.The main subject of paper is entrance of Croatian countries in the Kingdom of SHS and situation in the first years of the Kingdom of SHS existance. Based on accompanying literature author presents several theses. First thesis is that the unification of the State SHS with Kingdom of Serbia did in the unfavorable way for the Croatian countries. In continuation of paper author explains proces of forming a government and struggle of Croatian political parties for the increasing the rights of the Croatian people and political equality. Then author describes socio-political life in the Croatian countries and argues the thesis about bad attitude of the government to Croatian people in economic, religious and cultural issues. On the end of paper author makes a concluding thesis which means that struggle of Croatian politicans for reorganization of the state on the principle of equality did not succeed, moreover, it ends in tragic way and as a result, it appears in certain Croatian politicans in emigration idea of revolutionary struggle for collapse of the Kingdom SHS/Kingdom of Yugoslavia and the emergence
of independent Croatian country
Spark plasma sintering of ZrB2-ZrC powder mixtures synthesized by MA-SHS in air
No full textMechanical activation-assisted self-propagating high-temperature synthesis (MA-SHS) in air was successfully applied to the synthesis of the powder mixtures of ZrB2 and ZrC as a precursor of the ZrB2–ZrC composite. When the powder mixtures of Zr/B/C = 4/2/3–6/10/1 in molar ratio were mechanically activated (MA) by ball milling for 45–60 min and then exposed to air, they self-ignited spontaneously and the self-propagating high-temperature synthesis (SHS) was occurred to form ZrB2 and ZrC. The ZrB2–ZrC composites were produced from these MA-SHS powders by spark plasma sintering (SPS) at 1800 °C for 5–10 min and showed the fine and homogeneous microstructure composed of the <5 μm-sized grains. The mechanical properties of the composites evaluated by Vickers indentation method showed the values of Vickers hardness of 13.6–17.8 GPa and fracture toughness of 2.9–5.1 MPa·m1/2, depending on the molar ratio of ZrB2/ZrC. Thus, the better microstructure and mechanical properties of the ZrB2–ZrC composites were obtained from the MA-SHS powder mixtures, compared with those obtained from the MA powder, the mixing powder and the commercial powder mixtures
MA-SHS of ZrC and ZrB2 in Air from The Zr/B/C Powder Mixtures
No full textWhen the powder mixtures of Zr/B/C=3/2/2~6/10/1 in molar ratio were mechanically activated (MA) by ball milling and then exposed to air, they self-ignited spontaneously and the self-propagating high-temperature synthesis (SHS) was occurred to form ZrC and ZrB2 simultaneously. In this MA-SHS process in air, it is essential that graphite is converted into disordered carbon by mechanical activation and mixed with the particles of Zr and B in an intimate contact state. A fine, homogeneous microstructure of the product is expected to be a promising candidate as precursor of ZrC-ZrB2 composites.Key Engineering Materials, Volume 264-26
Fabrication of SPS compacts from NbC-NbB2 powder mixtures synthesized by the MA-SHS in air process
No full textWhen the powder mixture of Nb/B/C = 2/2/1 in molar ratio was mechanically activated (MA) by ball milling for 105 min and then exposed to air, it self-ignited spontaneously and the self-propagating high-temperature synthesis (SHS) was induced. The powder mixture of NbC and NbB2 was obtained by this MA–SHS in air process and then sintered by spark plasma sintering (SPS) at a temperature as low as 1800 °C. The sintered NbC/NbB2 composite compact showed the fine, homogeneous microstructure consisting of the a few μm-sized grains and the Vickers hardness of 19.8 GPa, which was higher than 14.3 and 16.6 GPa for the NbC/NbB2 composite compacts sintered from the powder mixture of Nb/B/C = 2/2/1 without MA–SHS and from the commercial powder mixture of NbC/NbB2 = 1/1
Pravna narava Države in Kraljestva/Kraljevine SHS v konfliktu jugoslovanskih ideologij
No full textAcstract: The main thesis of the article is that the differences in the interpretations of the legal natures of the State of Slovenes, Croats and Serbs and the Kingdom of Serbs, Croats and Slovenes were not the consequence of legal uncertainty, but rather reflected yet another among the many political battles in the conflict between the opposing Yugoslav ideologies. The author uses the international and constitutional criteria to analyse the dilemmas regarding the legal nature of the State of SHS and the legal (dis)continuity between the Kingdom of Serbia and the Kingdom of SHS. He argues that: 1) the State of SHS satisfied the fundamental requirements to be considered as a state; and 2) the Kingdom of SHS was a new state, as it was not created according to the standards of the Serbian Constitution. Moreover, it suspended the constitutional continuity of the Kingdom of Serbia.Izvleček: Glavna teza prispevka je, da razlike v razlagi pravne narave tako Države kot tudi Kraljevine Srbov, Hrvatov in Slovencev niso bile posledica pravne negotovosti, temveč so bile le odraz še ene med številnimi političnimi bitkami v vojni nasprotujočih si jugoslovanskih ideologij. Avtor uporablja mednarodna in ustavna merila ter analizira dileme glede pravne narave države SHS in pravne (dis)kontinuitete med Kraljevino Srbijo in Kraljevino SHS. Avtor na temelju analize argumentira, da: 1) je država SHS izpolnjevala temeljne kriterije državnosti in jo lahko smatramo kot državo, ter da 2) je bila Kraljevina SHS nova država, saj ni bila ustvarjena v skladu s standardi prejšnje srbske ustave; ravno nasprotno, Kraljevina SHS je prekinila ustavno kontinuiteto Kraljevine Srbije
Secondhand smoke (SHS) exposures: Workplace exposures, related perceptions of SHS risk, and reactions to smoking in catering workers in smoking and nonsmoking premises
No full textIntroduction: Smoke-free workplace legislation often exempts certain venues. Do smoking (exempted) and nonsmoking (nonexempted) catering premises' workers in Hong Kong report different perceptions of risk from and reactions to nearby smoking as well as actual exposure to secondhand smoke (SHS)? Methods: In a cross-sectional survey of 204 nonsmoking catering workers, those from 67 premises where smoking is allowed were compared with workers from 36 nonsmoking premises in Hong Kong on measures of perceptions of risk and behavioral responses to self-reported SHS exposure, plus independent exposure assessment using urinary cotinine. Results: Self-reported workplace SHS exposure prevalence was 57% (95% CI = 49%-65%) in premises prohibiting and 100% (95% CI = 92%-100%) in premises permitting smoking (p < .001). Workers in smoking-permitted premises perceived workplace air quality as poorer (odds ratio [OR] = 9.3, 95% CI = 4.2-20.9) with higher associated risks (OR = 3.7, 95% CI = 1.6-8.6) than workers in smoking-prohibited premises. Workers in smoking-prohibited premises were more bothered by (OR = 0.2, 95% CI = 0.1-0.5) and took more protective action to avoid SHS (OR = 0.2, 95% CI = 0.1-0.4) than workers in smoking-permitted premises. Nonwork exposure was negatively associated with being always bothered by nearby smoking (OR = 0.3, 95% CI = 0.1-0.9), discouraging nearby smoking (OR = 0.5, 95% CI = 0.2-1.1), and discouraging home smoking (OR = 0.4, 95% CI = 0.2-0.9). Urinary cotinine levels were inversely related to workers' avoidance behavior but positively related to their perceived exposure-related risks. Conclusions: Different workplace smoking restrictions predicted actual SHS exposure, exposure-related risk perception, and protective behaviors. Workers from smoking-permitted premises perceived greater SHS exposure-related risks but were more tolerant of these than workers in smoking-prohibited premises. This tolerance might indirectly increase both work and nonwork exposures. © The Author 2011. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved.postprin
Multiple linear regression analyses predicting subjective well-being (SHS) with gender and age in step 1, the five factors of personality (NEO-FFI in Sample 1 and BFPTSQ in Sample 2) in step 2, and the five scales of mindfulness (FFMQ) in step 3.
No full textMultiple linear regression analyses predicting subjective well-being (SHS) with gender and age in step 1, the five factors of personality (NEO-FFI in Sample 1 and BFPTSQ in Sample 2) in step 2, and the five scales of mindfulness (FFMQ) in step 3.</p
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