Aggregate Performance Research Articles

Prospect of CO2 sequestration in Malaysia cement industry

Carbon Dioxide (CO2), a known greenhouse gas, is the most influential driver of climate change. Tolerable amounts of CO2 emission are naturally produced through respiration, volcanic eruption, and organic matter decompositions. However, excessive emission of CO2 by human activities such as deforestation, changes in land use, construction, and energy-generating processes eventually increases the earth’s temperature and results in irreversible global climate change. In line with the Paris Agreement’s aim to limit the impact of climate change, numerous research is undertaken globally to identify ways to reduce man-made CO2 emissions. This paper discusses several potential CO2 sequestrations through CO2 utilization in the cement industry and their applicability for adoption in Malaysia as part of carbon emission reduction; fresh concrete, masonry bricks, cement bonded fibreboard, recycled masonry aggregate, recycled concrete aggregate and ultra-high performance concrete.

How can chokeberry (Aronia) (poly)phenol-rich supplementation help athletes? A systematic review of human clinical trials.

Athletes are increasingly consuming (poly)phenol supplements to modify oxidative stress and/or exercise-induced inflammation, in the hope that this will enhance exercise performance. Chokeberries are rich in (poly)phenols and may therefore influence the health and performance of athletes. The objective of this systematic review was to comprehensively explore the effects of chokeberry supplementation on performance and exercise-induced biomarkers of oxidative stress, inflammation, and haematology in the athletic population. A search was conducted in PubMed, Web of Science, and SCOPUS. Studies were included if the participants were athletes, supplemented with chokeberry or chokeberry-based products, and evaluated sports-related outcomes. A total of ten articles were included in the study. The participants of all the studies were athletes and included rowers, football players, handball players, triathletes, and runners. A qualitative comprehensive summary of the applications of chokeberry supplementation targeting the athletic population has been evaluated. This included the effect of chokeberry supplementation on redox status, exercise-induced inflammation, haematology, iron metabolism, platelet aggregation, metabolic markers, body composition, and exercise performance. Chokeberry (poly)phenol-rich supplementation may be effective in enhancing the redox balance of athletes, yet more evidence is required to provide solid conclusions on its effect on inflammation, platelet function, iron metabolism and exercise performance.

Study on the development of a rotary soil softener

This article presents the technological working process of the rotary softener developed for the chisel-cultivator; results of experimental studies carried out to justify its parameters. The type of soil and its physic-mechanical properties are the main factors in the selection of the working bodies of the soil tillage machine and assessment of aggregate performance. The researches are carried out mainly in grassy, pale gray and barren soils, and the physic-mechanical properties of the soil in irrigated fields of the Republic of Uzbekistan have been sufficiently studied. However, in a short period of time, machines that can treat a large area with high quality and at the level of demand have not been created. In order to choose the optimal type of rotary softener, based on the physical and mechanical properties of the soil, rotors equipped with different types of blades were prepared and tested. A rotary tiller for a chisel cultivator was compared with a chisel tiller and leveler, and cost effectiveness, labor and operating costs were calculated.

Use of Multi-Scale Investigation to Evaluate Adhesion Performance of Warm-Mix Polymer-Modified Asphalt

Warm Mix Asphalt (WMA) technology can effectively reduce carbon emissions and energy consumption during road project construction. However, it may have a negative impact on the binding properties of asphalt mixtures. In order to effectively evaluate the adhesion performance of asphalt binders and aggregates under the combined influence of WMA and traditional polymer-modified asphalt, this paper provides a comprehensive evaluation at the micro and macro levels. The adhesion between three different modified asphalts (warm mix crumb rubber/ Styrene-Butadiene-Styrene (SBS) composite modified asphalt, warm mix crumb rubber asphalt, and warm mix SBS modified asphalt) and two different aggregates (limestone and granite) under both virgin and short-term aging conditions were analyzed. Regardless of the type of modified asphalt, the results showed that limestone aggregates have better adhesion properties with asphalt binders. In addition, the short-term thermal oxidation aging behavior is conducive to enhancing the asphalt-aggregate adhesion characteristics. Furthermore, WMA additives, crumb rubber, and SBS compound modification can improve the adhesion performance between asphalt and aggregate.

An impulsive and switched system based maintenance plan optimization in building energy retrofitting project

The maintenance time schedule optimization into the investment budget decision for building energy retrofitting and maintenance planning is incorporated. The aggregate performance and population dynamics of the totality of retrofitted items is described by an impulsive switched system model. The items are switched to different working states by maintenance actions with impulsive effects. Considering the retrofitting project with deterioration. The objective of optimal maintenance control is to maximize the overall energy savings and financial payback. The optimal maintenance control problem is showed to be feasible and bounded. The maintenance time schedule and intensities are simultaneously optimized by an improved differential evolution (DE) algorithm. Compared with the fixed maintenance time schedule, the proposed approach is validated by simulation results, specifically, 3.36% of energy saving and 23.09% of internal rate of return (IRR) can be improved.

The Feasibility Analysis of Recycled Aggregates from Construction and Demolition Waste for Permeable Pavement

For reusing the construction and demolition waste (C&DW) materials and solving waterlogging problems, the feasibility of applying C&DW to the permeable pavement (PP) was investigated. The recycled brick aggregate (RBA) and recycled concrete aggregate (RCA) were used as PP base materials under different mixing ratios and grades. Geotextiles were also used in this study as filter contaminants. Modified compaction tests, rainfall model tests, and column leaching tests were conducted on a total of 15 samples with three gradations and five RBA and RCA mix ratios. The specimens for the rainfall model test were compacted at around optimum moisture content, and the degree of compaction was 97%. Using the sub-layer compaction method, each group of samples is compacted in five layers in strict accordance with the specifications. In general, C&DW has the potential to be used underground without pollution to the groundwater. The heavy metal concentrations in C&DW are less than in the local soil and related to material resources. The water yield performance was the best when 100% concrete was used to build PP, and the total water storage was the most when 100% of bricks were chosen to make PP. Due to the excellent permeability, C&DW can be selected for pavement fillers. The geotextile reduces the permeability by about 13% but effectively filters out more than 50% of the fine particles in the rainfall. The permeability performance of concrete aggregates may be better than that of bricks, and fine particles can reduce the permeability.

Optimization design and performance evaluation of a novel asphalt rejuvenator

The development of a regeneration agent is one of the key technologies for pavement regeneration and one of the methods to reduce carbon emissions in the transportation field, so it is very necessary to develop a regeneration agent. Based on the composition of asphalt and rejuvenator components, the optimal dosing of extraction oil, plasticizer dioctyl phthalate (DOP), and hydrogenated (carbon 9) C9 petroleum resin was determined by the response surface method, and the suitable dosing of the anti-aging agent was also designed to optimize the orthogonal experiment to prepare the ZJ-I (Zenith Yummy-Invent) rejuvenator with good overall performance. On the basis of the ZJ-I rejuvenator, dynamic shear rheology (DSR), bending beam rheometery (BBR), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and contact angle experiments were used to investigate the effects of the ZJ-I rejuvenator dosing on the high- and low-temperature rheology, chemical structure, surface microscopic morphology, and adhesion between asphalt and aggregate of aged asphalt and to explore the regeneration effect and regeneration mechanism of the ZJ-I rejuvenator. The results showed that the ZJ-I rejuvenator formulated with 83.6% extracted oil, 15% plasticizer DOP, 1.4% hydrogenated petroleum resin, 0.6% antioxidant, and 0.4% light stabilizer has the best regeneration effect, and its optimal dosing is 7% aging degree. It can also improve the adhesion performance of asphalt and aggregate.

Network-based risk assessment of country-level sustainable development goals

The Sustainable Development Goal (SDG) index is an aggregate performance measure of the progress of individual countries in achieving 17 SDGs covering economic, social and environmental dimensions of sustainability. Using a data-driven probabilistic approach, this study aims to model the risks associated with individual SDGs in a network setting and establish the relative importance of SDGs in predicting the aggregate SDG index. Further, SDGs are prioritized relative to their impact on the SDG index while considering the two extreme risk states of individual SDGs. ‘Clean water and sanitation’ and ‘quality education’ goals have the highest diagnostic value relative to the ‘high performance’ and ‘low performance’ state of the SDG index, respectively. The network comprising the risks associated with individual SDGs is most vulnerable to ‘quality education’, whereas ‘no poverty’ can significantly reduce the network-wide impact. Further, the two ranking schemes regarding the vulnerability and resilience potential of individual SDGs represent quite different rankings for a few SDGs, such as ‘life on land’, ‘partnerships for the goals’, ‘peace, justice and strong institutions’ and others. The network model developed provides insights to policy-makers by establishing causal relationships among SDGs. For instance, ‘good health and well-being’, ‘sustainable cities and communities’, ‘peace, justice and strong institutions’ and ‘partnerships for the goals’ are mutually interdependent. Similarly, other causal relations exist within the network.

Financial Inclusion in West African Economic and Monetary Union’s Economies: Performance Analysis Using Data Envelopment Analysis

A data envelopment analysis (DEA) has yet to be chosen to assess countries’ financial inclusion levels. We introduce an application of the DEA methodology to compute aggregate performance measures regarding the financial inclusion of economies. We specifically explore composite scores based on relative efficiency, super-efficiency, and cross-efficiency approaches. We implement the proposed procedure to study the financial inclusion in nations from the West African Economic and Monetary Union (WAEMU). We use the Union’s Central Bank’s financial inclusion data from 2010 to 2017. We obtain robust financial inclusion level measures, showing that overall, in the Union, there have been steady improvements during the study period, but with heterogenous behavior at the level of each economy. A benchmarking analysis allowed us to determine the countries with the best practices. For the remaining nations, we find their reference countries. Finally, we identified which financial service sectors drive the financial inclusion in each country from the optimal weights of the DEA model.

Aggregation and dehydration of excavated soft clay and use for subgrade engineering-part 2: A pilot-scale study

This paper presented a pilot-scale investigation into the performance of stabilized-soil aggregates for subgrade, which was generated from dehydration and aggregation of excavated soft clay. The evaluation work consisted of three parts. Firstly, an industrialized production line, aiming to produce aggregates efficiently was established. The produced aggregates were then employed to construct a trial embankment. Finally, a series of in-situ tests were performed on the product and embankment to evaluate the suitability of the manufactured product for subgrade engineering. It was found that the technique proposed in the companion paper was also feasible on an industrial scale, and the dehydration rate was around 68 % of the laboratory scale, which was considerably higher than natural drying. Although the dehydration rate was decreased by a certain amount, enlarging the production scale from precisely controlled laboratory scale to field pilot scale had little effect on the engineering properties of products. After dehydration and aggregation, the high plasticity clayey soil was transformed into low plasticity silty soil, showing excellent soaked CBR values (over 30 %). When used within the embankment, the constructed embankment exhibited reliable stiffness (e.g., DCPI ≤ 4.2 mm/blow and Mr ＞ 70 MPa) and premium water stability, which could well satisfy the requirement of extremely heavy traffic load stated in the standards. The influences of such modification of soil characteristics on estimation of in-situ CBR values and selection of compaction methods were also discussed. Based on the discussion, some recommendations for proper use of the stabilized-soil aggregates on subgrade engineering at an industrial scale were given.

The network origins of aggregate fluctuations: A demand-side approach

We construct a model of cyclical growth with agent-based features designed to study the network origins of aggregate fluctuations from a demand-side perspective. In our model, aggregate fluctuations result from variations in investment behaviour at firm level motivated by endogenously-generated changes in ‘animal spirits’. In addition to being influenced by their own economic conditions, firms pay attention to the performance of first-degree network neighbours, weighted (to differing degrees) by the centrality of these neighbours in the network, when revising their animal spirits. This allows us to analyse the effects of the centrality of linked network neighbours on the amplitude of aggregate fluctuations. We show that the amplitude of fluctuations is significantly affected by the eigenvector centrality, and the weight attached to the eigenvector centrality, of linked network neighbours. The dispersion of this effect about its mean is shown to be similarly important, resulting in the possibility that network properties can result in ‘great moderations’ giving way to sudden increases in the volatility of aggregate economic performance.

Aggregation and dehydration of excavated soft clay and use for subgrade engineering–Part 1: A laboratory study

The reuse of the excavated soil for subgrade construction, as an alternative to the traditional excavated soil management approach, has demonstrated great potential for engineering application. However, its application is currently hindered by the poor engineering properties of soft soils and the pretreatment process. In this paper, an improved technique employing aggregation and dehydration for rapid stabilization of excavated soft clay was proposed. By wet mixing with stabilizers, excavated soft clay was transformed into separated aggregates with the larger surface areas exposed to air. During turning preservation, aggregates were further stabilized and dehydrated as a result of the combined hydration and enhanced evaporation effect. The performance of the produced stabilized-soil aggregates was explored by performing a series of laboratory tests and it was demonstrated that by enhancing the evaporation effect, moisture content of excavated soft clay decreased by over 20 % in 4 days. Through the aggregation effect, the soft clay tended to be silty in the plasticity chart and experienced an increase in optimal moisture content and a decrease in maximum dry density. Unconfined compressive strength and Californian bearing ratio tests showed that compacted aggregates exhibited reliable strength and water stability because of the enhanced cementitious and pozzolanic reactivity, which was capable for various sections of the subgrade with different classifications. Meanwhile, the performance of compacted aggregates was found to be dominated by the stabilizer content and the characteristics of the raw soil, which indicates that it would be preferred to distinguish the stabilizer dosage and the excavated soft clay to counter different requirements for engineering application. And a draft, dry and thermostatic environment for turning preservation is highly recommended for the purpose of improving the efficiency of excavated soil management.

Structural Characteristics and Sound Absorption Properties of Waste Hemp Fiber

In order to realize high-efficiency and high-value recycling of waste hemp fibers, the macromolecular structure, the supramolecular structure, and the morphological structure of waste hemp fibers were investigated by using Fourier transform infrared spectroscopy, X-ray diffractometry, upright metallurgical microscopy, and scanning electron microscopy. According to its structural characteristics, the sound-absorbing mechanism of waste hemp fiber was analyzed, and the reason for the good sound-absorbing performance of waste hemp fiber was clarified. The acoustic impedance transfer function test was used to analyze and compare the sound-absorbing performance of waste hemp fiber and several other fiber aggregates that could be used in the field of sound-absorbing, and the sound-absorbing performance of a waste hemp fiber composite material was tested. The research revealed that: the sequence of sound-absorbing performance of several fiber aggregates was cotton fiber, waste hemp fiber, wool fiber, and polyester fiber; that waste hemp fiber had excellent high-frequency sound-absorbing performance, with a maximum sound absorption coefficient of 0.95; and that the maximum sound absorption coefficient of the waste hemp fiber composite reached 0.93. Therefore, the waste hemp fiber has excellent sound-absorbing properties and has high application value in the field of sound absorption.

A new modified obstetric early warning score for prognostication of severe maternal morbidity

BackgroundMaternal mortality is still a major challenge for health systems, while severe maternal complications are the primary causes of maternal death. Our study aimed to determine whether severe maternal morbidity is effectively predicted by a newly proposed Modified Obstetric Early Warning Score (MOEWS) in the setting of an obstetric intensive care unit (ICU).MethodsA retrospective study of pregnant women admitted in the ICU from August 2019 to August 2020 was conducted. MOEWS was calculated 24 h before and 24 h after admission in the ICU, and the highest score was taken as the final value. For women directly admitted from the emergency department, the worst value before admission was collected. The aggregate performance of MOEWS in predicting critical illness in pregnant women was evaluated and finally compared with that of the Acute Physiology and Chronic Health Evaluation II (APACHE II) score.ResultsA total of 352 pregnant women were enrolled; 290 women (82.4%) with severe maternal morbidity were identified and two of them died (0.6%). The MOEWSs of women with serious obstetric complications were significantly higher than those of women without serious obstetric complications [8(6, 10) vs. 4(2, 4.25), z = -10.347, P < 0.001]. MOEWSs of 24 h after ICU admission had higher sensitivity, specificity and AUROC than MOEWSs of 24 h before ICU admission. When combining the two MOEWSs, sensitivity of MOEWS was 99.3% (95% CI: 98–100), specificity 75.8% (95% CI: 63–86), positive predictive value (PPV) 95.1% (95% CI: 92–97) and negative predictive value (NPV) 95.9% (95% CI: 86–100). The areas under the receiver operator characteristic (ROC) curves of MOEWS were 0.92 (95% CI: 0.88–0.96) and 0.70 (95% CI: 0.63–0.76) of the APACHE II score.ConclusionThe newly proposed MOEWS has an excellent ability to identify critically ill women early and is more effective than APACHE II. It will be a valuable tool for discriminating severe maternal morbidity and ultimately improve maternal health.

Accelerating Backward Aggregation in GCN Training With Execution Path Preparing on GPUs

The emerging Graph Convolutional Network (GCN) has now been widely used in many domains, and it is challenging to improve the efficiencies of applications by accelerating the GCN trainings. For the sparsity nature and exploding scales of input real-world graphs, state-of-the-art GCN training systems (e.g., GNNAdvisor) employ graph processing techniques to accelerate the message exchanging (i.e. aggregations) among the graph vertices. Nevertheless, these systems treat both the aggregation stages of forward and backward propagation phases as all-active graph processing procedures that indiscriminately conduct computation on all vertices of an input graph. In this paper, we first point out that in a GCN training problem with a given training set, the aggregation stages of its backward propagation phase (called as backward aggregations in this paper) can be converted to partially-active graph processing procedures, which conduct computation on only partial vertices of the input graph. By leveraging such a finding, we propose an execution path preparing method that collects and coalesces the data used during backward propagations of GCN training conducted on GPUs. The experimental results show that compared with GNNAdvisor, our approach improves the performance of the backward aggregation of GCN trainings on typical real-world graphs by 1.48x~5.65x. Moreover, the execution path preparing can be conducted either before the training (during preprocessing) or on-the-fly with the training. When used during preprocessing, our approach improves the overall GCN training by 1.05x~1.37x. And when used on-the-fly, our approach improves the overall GCN training by 1.03x~1.35x.

Preoperative priming results in improved operative performance with surgical trainees

BackgroundPreoperative warm-up regimens are increasingly utilised in the surgical field, however no consensus on benefits of priming across surgical experience has been realised. The aim of this study was to evaluate the impact of simulation preoperative priming on operative performance across levels of resident experience. MethodsA single-blinded randomised control trial was carried out in a regional surgical training centre. Volunteers were randomised to undergo simulated surgical warm-up procedure prior to their first case as primary operator or proceed directly to surgery. ResultsPerformances of 147 operative procedures were collected over an 18 month period, experience ranging from PGY2-PGY 7. Senior participants consistently outperformed junior residents in unprimed operative cases (p = 0.005). In primed operative performances no significant difference in aggregate performance scores was found (p = 0.07). ConclusionPriming confers a greater advantage to junior residents with particular regard to generic surgical skills. Senior residents demonstrate improved self-efficacy scores measured following priming.

Exploring the carbon capture and sequestration performance of biochar-artificial aggregate using a new method

To achieve the ambitious goal of carbon neutrality, more carbon sequestration channels need to be developed. In this study, we tried to combine biochar with cold-bonded artificial lightweight coarse aggregate (ALCA) which is made from municipal solid household waste incineration bottom ash (MSWIBA).The strong carbon capture ability of biochar was used to attract external CO2 into the interior of ALCAs, which combined with CaO in MSWIBA to form CaCO3 to achieve the effect of chemical carbon sequestration. The total carbon sequestration and carbon sequestration rate of biochar-ALCAs were quantified by a self-designed CO2 concentration change test box, the physical and mechanical properties of biochar-ALCAs were investigated, as well as the changes before and after carbonization. The results showed that biochar and ALCAs had good synergistic carbon sequestration ability. The total carbon sequestration of biochar-ALCAs could reach 30.58–33.06 kg/ton. The carbon sequestration efficiency could reach 70.2 % and 84.9 % at 28 d/56 d in a low CO2 concentration environment (0.05 % VOL). In addition, the water absorption of biochar-ALCAs decreased by 4.3 %–13.9 %, the apparent density increased by 0.9 %–2.8 %, and the strength increased by 4.3 %–7.0 % after carbon sequestration, and the physical and mechanical properties were significantly improved. The purpose of this paper is to investigate the synergistic carbon sequestration of biochar in combination with ALCAs and to quantitatively assess its ability to solidify low concentrations of CO2 in the natural environment. A new test apparatus and test method were designed for this purpose. This paper may contribute for an important advance on the preparation of recyclable cement-type composites able to capture and solidify CO2 from the natural environment.

Constructing Divisia Monetary Aggregates for Nigeria

This study computes Divisia monetary aggregates DM1, DM2, and DM3 for Nigeria using the Tornqvist-Theil quantity index for the period 2007M12 to 2020M12 and evaluates the performance of the higher-order aggregate (DM3) with a corresponding higher aggregate of the simple sum broad money supply (M3). Applying the indicators to money demand function the results showed that DM3 performed better than the matching simple sum measure M3 due to its faster convergence rate. This is because the Divisia aggregates contain additional information in the form of user-costs and spending shares that are not considered in the compilation of the traditional measure, information that may be important for the proper execution of monetary policy. It is therefore, recommended that the Divisia broad money index be used as complement to the simple sum broad money supply for policy decisions.

Mix design development of fly ash-GGBS based recycled aggregate geopolymer concrete

Concrete is the most extensively used building material across the world. It can accommodate huge volumes of industrial waste by-products such as fly ash, ground granulated blast furnace slag, and construction and demolition waste which are generated in massive quantities from thermal power plants, steel plants, as a by-product, and construction waste debris respectively. Lots of fly ash, ground granulated blast furnace slag, and construction and demolition waste are discarded, creating environmental and storage issues. The manufacturing of recycled aggregate geopolymer concrete is one of the cost-effective ways to dispose vast amounts of debris. The use of recycled aggregate geopolymer concrete as structural concrete is not encouraged due to lack of appropriate mix design methodology. The current study aims to develop a new mix design methodology by using fly ash and ground granulated blast furnace slag with 100% recycle aggregate, which is simpler and more consistent than previous procedures. The suggested process has been further validated by developing a range of concretes with alkaline activate content to binder ratios ranging from 0.3 to 0.8. According to the present study, by using fly ash and ground granulated blast furnace slag along with recycled aggregate in concrete, compressive strength of an order of nearly 60 MPa can be obtained at the curing age of 28 days. SEM and XRD analysis were also carried out to evaluate the processes of polymerization. The results suggest that fly ash and ground granulated blast furnace slag have a superior synergetic influence on recycled aggregate geopolymer concrete performance.

Excitatory and inhibitory interactions affect the balance of chorus activity and energy efficiency in the aggregations of male frogs: Numerical simulations using a hybrid dynamical model

We numerically study the role of excitatory and inhibitory interactions in the aggregations of male frogs. In most frogs, males produce sounds to attract conspecific females, which activates the calling behavior of other males and results in collective choruses. While the calling behavior is effective for mate attraction, it requires high energy consumption. In contrast, satellite behavior is an alternative mating strategy in which males deliberately stay silent in the vicinity of a calling male and attempt to intercept the female attracted to the caller, allowing the satellite males to reduce their energy consumption while having a chance of mating. Here we propose a hybrid dynamical model in which male frogs autonomously switch among three behavioral states (i.e., calling state, resting state, and satellite state) due to the excitatory and inhibitory interactions. Numerical simulations of the proposed model demonstrated that (1) both collective choruses and satellite behavior can be reproduced and (2) the satellite males can prolong the energy depletion time of the whole aggregation while they split the maximum chorus activity into two levels over the whole chorusing period. This study highlights the importance of the multiple behavioral types and their transitions for the performance of the whole aggregation.