Initial Set Research Articles

Conversion of Rice Straw to Biochar Through Microwave Pyrolysis for its Use as Partial Replacement of Cement

Background: An experimental study was conducted to explore the feasibility of partially substituting biochar in cement, for making concrete mixture in civil infrastructures. The biochar was derived from the pyrolysis process in thermo-chemical conversion of the most under-utilized agricultural residue i.e. rice straw. Demand of cement is increasing day by day due to fast growth of construction sector all around the world. The current scenario of rampant on-farm burning of rice straw is a great concern not only for maintaining the fertility aspects of the cultivating land but also for the degradation of surrounding environment. Production of cement is equally very energy intensive and contributes a lot in emitting greenhouse gases, mostly carbon dioxide to the environment. An attempt was therefore made in the present study to partially replace the rice straw biochar with cement to reduce the production of the later and to evaluate the key performance parameters of biochar based concrete. Methods: The study was carried out in the Department of Agricultural Structures, Civil and Environmental Engineering, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India during 2021-22. Microwave assisted pyrolysis was followed for quick and efficient heating of the biomass feedstock. Efforts was also made to supply power to the microwave pyrolyser from a reliable source of power i.e. solar photovoltaic system for its popularization even in remote and off-grid rural areas. Result: The yield of biochar was found to be higher (about 28%) at 600 W input power to the microwave reactor and 15 minutes’ reaction time in the pyrolysis process of rice straw. The performance parameters of biochar based concrete such as initial setting times, final setting times and workability were found to be decreased by 8, 5 and 9% respectively and compressive, split tensile and flexural strengths were increased by 13, 18 and 5% respectively compared to the reference concrete. Biochar from rice straw can hence ultimately be utilized as partial replacement of cement for use in construction industry.

Alpha-2a adrenergic receptor activation in genetic absence epilepsy: An absence status model?

The objective of the study was to propose a candidate animal model of absence status epilepticus induced by specific alpha-2a adrenergic receptor (α2AR) activation. We also aim to investigate the responsiveness of this model to classical anti-status or anti-absence medications. An α2AR agonist, dexmedetomidine (DEX), was injected intracerebroventricularly into adult rats with genetic absence epilepsy, and their electroencephalography (EEG) was recorded. The total duration, number, and mean duration of each spike-and-wave discharges (SWDs) were evaluated. The blocks of absence status events were classified as the initial and second sets of absence statuses. Ethosuximide (ETX) was administered as a pretreatment to another group of rats and later injected with 2.5 μg DEX. In addition, ETX, valproic acid (VPA), diazepam (DIAZ), and atipamezole (ATI) were administered after induced status-like events following DEX administration. Power spectral characteristics and coherence analysis were performed on the EEG to assess the absence status events and sleep. The 2.5 μg dose of DEX increased the total SWD duration and induced continuous SWDs up to 26 min. Following the initial absence status event, sleep was induced; then, the second period of absence status-like activities were initiated. ETX pretreatment blocked the occurrence of absence status-like activities. Power spectral density analyses revealed that DEX-induced post-sleep activities had higher power in delta frequency band (1-4 Hz) and attenuated power of 7 Hz harmonics (14 and 21 Hz) than the pre-injection seizure. The mean duration of SWDs were decreased in all the groups, but occasional prolonged activities were seen in ETX or VPA-injected rats but not with DIAZ or ATI. This study presents an absence status epilepticus animal model that is activated by α2AR activation to investigate the pathophysiological role of absence status. Unlike other agents ATI switched off the second set of absence statuses to normal SWDs, without sedation or lethargy, can show it may preferentially block absence status-like activity. This study proposes a rat model for prolonged seizures, resembling absence status epilepticus. Activating the brain's alpha-2a adrenergic receptor with dexmedetomidine induced seizures lasting up to 26 minutes. Ethosuximide pretreatment and post-treatment with valproic acid, diazepam, and atipamezole decreased induced seizures. The findings suggest this model is valuable for studying absence status epilepticus. In addition, atipamezole normalized abnormal seizures without sedation, hinting at its potential for targeted treatment and further research.

Model predictive current control based on hybrid control set for permanent magnet synchronous motor drives

AbstractModel predictive current control (MPCC) has been widely recognized as a high‐performance scheme for permanent magnet synchronous motor drives because of its simple control structure. This article proposes a novel multivector MPCC (MMPCC) method based on a hybrid control set, which includes both original basic voltage vectors (VVs) and synthesized VVs. The two active VVs and one null VV are considered as an initial control set, and the exact combination of them depends on their corresponding durations, which are calculated by stator current slopes in frame with the use of the prediction formula. Contrary to the traditional cost function, an alternative hybrid control set can achieve superior voltage precision. This is due to the involved cost function that minimizes the maximum of prediction current errors, which typically occur at non‐integer sample instants during the control period. The performance of the proposed MMPCC method has been experimented to confirm its effectiveness, compared with the conventional MPCC (CMPCC) and duty‐cycle MPCC (DMPCC). The results indicated an anticipated enhancement in both dynamic and steady‐state performance at a low rotor speed, alongside a significant robustness against parameter mismatch.

Patterns of publicly funded naltrexone use among patients diagnosed with alcohol use disorder in Ontario.

Naltrexone is recommended first-line to manage alcohol use disorder (AUD). With previous studies indicating poor retention on naltrexone, we determined duration of naltrexone use and assessed the association between prescription setting and time to discontinuation in Ontario. We conducted a retrospective population-based cohort study among Ontario public drug beneficiaries diagnosed with AUD who initiated publicly funded naltrexone from June 2018 to September 2019. The primary outcome was time to naltrexone discontinuation, with a secondary analysis assessing receipt of at least one prescription refill. We used Cox proportional hazards models and logistic regression to test the association between prescription setting and each medication persistence outcome. Among 2531 new naltrexone patients with AUD, the median duration of naltrexone use was 31days and 394 (15.6%) continued naltrexone for 6months or longer. There was no association between setting of initiation and duration of naltrexone use; however, those initiating naltrexone following an acute inpatient hospital stay were more likely to fill a second prescription (aOR 1.43, 95% CI 0.96-2.14), while those initiating after an ED visit were less likely to be dispensed a second prescription (aOR = 0.69, 95% CI 0.52-0.90) compared to those starting in a physician's office. Persistence on naltrexone to treat an AUD is low, regardless of the setting of initiation. Further research is needed to elucidate the barriers encountered by patients with AUD that lead to poor treatment persistence in order to develop interventions that facilitate patient-centered access to evidence-based treatment for AUD in the province.

Ionic liquid-assisted preparation of Ag–Zn–In–S quaternary quantum dot thin films and luminescence performance optimized by machine learning

Machine learning-assisted synthesis of new materials has been an ongoing hot topic. Luminescent Ag–Zn–In–S quaternary semiconductor quantum dot thin films have great application potential in many fields because of their excellent photoelectric performance. In this study, an environmentally friendly ionic liquid-assisted approach was employed to prepare high-performance Ag–Zn–In–S luminescent thin films, and machine learning methods were applied to screen the optimal preparation conditions. The photoluminescence (PL) performance, crystal structure, and morphology of the thin films were also been studied. The initial data set was obtained by high-throughput experiments. By comparing machine learning algorithms of Xgboost, Random Forest, Bagging, SVM, Extra Tree, and Gradient Boosting, the Random Forest achieved the best accuracy (r = 0.84, R2 = 0.847) and was selected to predict the optimal preparation conditions of Ag–Zn–In–S quaternary quantum dot thin films. The machine learning predicted results are in great agreement with the subsequent experimental results, which verifies the accuracy and effectiveness of the machine learning model. This study offers a theoretical foundation for preparing optimal inorganic quantum dot luminescent materials using machine learning.

Multi-agent cooperative swarm learning for dynamic layout optimisation of reconfigurable robotic assembly cells based on digital twin

AbstractTo meet the requirement of product variety and short production cycle, reconfigurable manufacturing system is considered as an effective solution in addressing current challenges, such as increasing customisation, high flexibility and dynamic market demand. Dynamic factory layout design and optimisation are the crucial factors in response to rapid change in the mechanical structure, software and hardware integration, as well as production capability and functionality adjustment. Nevertheless, in the current research, the layout design for reconfigurable manufacturing systems is usually simplified with autonomous devices being regarded as 2D shapes. Issues such as overlapping and transportation distance are also addressed in an approximate form. In this paper, we present a novel multi-agent cooperative swarm learning framework for dynamic layout optimisation of reconfigurable robotic assembly cells. Based on its digital twin established in the proposed learning environment (constructed in Visual Components and controlled by TWINCAT), the optimisation framework uses 3D digital representation of the facility models with minimal approximation. Moreover, instead of using a traditional centralised learning manner, multi-agent system could provide an alternative way to address the layout issues combined with the proposed decentralised multi-agent cooperative swarm learning. In order to verify the application feasibility of the learning framework, two aerospace manufacturing use cases were implemented. In the first use case, the layout compactness is reduced by 3.8 times compared with the initial layout setting, the simulated production time is reduced by 2.3 times, and the rearrangement cost decreased by 33.4$$\%$$ % . In addition, all manufacturing activity within the cell can be achieved with a feasible robot path, meaning without any joint limits, reachability or singularity issue at each key assembly point. In the second use case, we demonstrated that with the proposed dynamic layout optimisation framework, it is possible to flexibly adjust learning objectives by selecting various weight parameters among layout compactness, rearrangement cost and production time.

Flow over a stretchable cylinder with nonlinear heat sources/sinks: Magnetic dipoles application

This work contributes mainly an analysis of the impact of a generated magnetic dipole on the magneto heat transport inside a deformable cylinder. Magnetic dipole signifies, magnotherapy and spectroscopy which are medical applications, generate static magnetic fields. The investigation considers the influence of non-linear heat sources and sinks, which result in a noteworthy phenomenon. The flow field is governed by accurate and nondimensional factors, which are used to convert the initial set of highly nonlinear and coupled partial differential equations into a set of nonlinear ordinary differential equations. These nonlinear ordinary differential equations are then solved mathematically using the bvp4c function in MATLAB, taking into account the boundary conditions. Ultimately, this section provides an overview of the ramifications stemming from various physical constraints on the movement of fluids, including nonlinear source/sink effects and other more factors. Ultimately, the discovered results that impose limitations are juxtaposed with those documented in the scientific literature, revealing a significant connection.

Consensus Statements among European Sleep Surgery Experts on Snoring and Obstructive Sleep Apnea: Part 1 Definitions and Diagnosis.

Seeking consensus on definitions and diagnosis of snoring and obstructive sleep apnea (OSA) among sleep surgeons is important, particularly in this relatively new field with variability in knowledge and practices. A set of statements was developed based on the literature and circulated among eight panel members of European experts, utilizing the Delphi method. Responses in agreement and disagreement on each statement and the comments were used to assess the level of consensus and develop a revised version. The new version with the level of consensus and anonymized comments was sent to each panel member as the second round. This was repeated a total of five rounds. The total number of statements included in the initial set was 112. In the first round, of all eight panelists, the percentage of questions that had consensus among the eight, seven, and six panelists were 45%, 4.5%, and 7.1%, respectively. In the final set of statements consisting of 99, the percentage of questions that had consensus among the 8, 7, and 6 panelists went up to 66.7%, 24.2%, and 6.1%, respectively. Delphi's method demonstrated an efficient method of interaction among experts and the establishment of consensus on a specific set of statements.

Joint synthesis of trajectory and controlled invariant funnel for discrete‐time systems with locally Lipschitz nonlinearities

AbstractThis paper presents a joint synthesis algorithm of trajectory and controlled invariant funnel (CIF) for locally Lipschitz nonlinear systems subject to bounded disturbances. The CIF synthesis refers to a procedure of computing controlled invariance sets and corresponding feedback gains. In contrast to existing CIF synthesis methods that compute the CIF with a predefined nominal trajectory, our work aims to optimize the nominal trajectory and the CIF jointly to satisfy feasibility conditions without the relaxation of constraints and obtain a more cost‐optimal nominal trajectory. The proposed work has a recursive scheme that mainly optimize trajectory update and funnel update. The trajectory update step optimizes the nominal trajectory while ensuring the feasibility of the CIF. Then, the funnel update step computes the funnel around the nominal trajectory so that the CIF guarantees an invariance property. As a result, with the optimized trajectory and CIF, any resulting trajectory propagated from an initial set by the control law with the computed feedback gain remains within the feasible region around the nominal trajectory under the presence of bounded disturbances. We validate the proposed method via two applications from robotics.

Adaptive terminal sliding mode trajectory tracking control with fixed‐time prescribed performance considering rollover stability of autonomous vehicles

SummaryIn the face of external disturbances, the autonomous vehicle with a high center of gravity is exposed to the risk of roll instability during trajectory tracking. To this end, this paper aims to propose a vector‐extended‐state‐observer (VESO)‐based adaptive fixed‐time terminal sliding mode prescribed performance control strategy, which coordinates the front wheel steering angle and external roll moment to ensure the roll stability of the high center of gravity autonomous vehicle while improving the tracking dynamic and steady state performances. The VESO for estimating the external disturbance is designed to enhance the robustness outside the sliding mode surface, based on which the adaptive updating laws compensate the estimation errors to provide the control system's dynamic performance. A fixed‐time sliding mode control with prescribed performance is proposed, which combines a fixed‐time prescribed performance control method to further improve the transient performance and steady‐state accuracy. The double lane‐changing reference trajectory tracking conditions under different vehicle driving speeds and initial errors settings are verified by simulation in MATLAB/Simulink environment, and the results show that the proposed control strategy can ensure the rolling stability of the vehicle, can track the reference trajectory accurately and quickly, and has strong robustness.

Early strength enhancement of high-volume fly ash mortar using accelerating admixtures

High-volume fly ash mortar is considered a "green" material, a sustainable development solution for the construction industry, in which the fly ash replacement Portland cement content is over 50%. However, this material has the major disadvantage of slow strength development, especially at an early age, which limits its applicability. To overcome the above disadvantage, the individual or combined addition of lime Ca(OH)2, silica fume, and/or accelerating admixtures including sodium thiocyanate (NaSCN), diethanolamine (DEA), and glycerol (Gly), etc. have been interested recently. In this study, to enhance the early strength of mortars with fly ash content to replace 60÷80% of Portland cement, a three-component accelerating admixture of NaSCN, DEA, and Gly (2:1:0.5 by the mass) was used with different ratios of 0.21÷0.49 % by the total powder mass, combined with a reasonable amount of lime, silica fume supplement as presented in previous research. Experimental results showed that the optimal accelerating admixture content is 0.35% by weight of powder, combined with 6% silica fume and the additional amount of lime is 5%; 10%; and 15% corresponding to mortars using fly ash of 60%; 70% and 80%, respectively to improve early strength of mortars that are suitable for structural use (R3 ≥ 13MPa, 3 days old). In addition, the influence of the additives used on the initial setting time of high-volume fly ash mortars was also discussed.

The decoupling relationship between land use efficiency and carbon emissions in China: An analysis using the Socio-Ecological Systems (SES) framework

The Socio-Ecological Systems (SES) framework provides a comprehensive approach to studying the decoupling of land use efficiency (LUE) and carbon emissions (CEs), thereby supporting the transition towards low-carbon land use from a holistic social-ecological perspective. In this study, we utilized the SES framework to examine the decoupling patterns of LUE and CEs across different land use categories (agricultural, industrial, commercial, and ecological land) in 285 Chinese cities from 2007 to 2019. We found that: (1) The decoupling relationships between LUE and CEs varied across different land categories, influenced by input/output values as well as social, economic, and regulatory factors. (2) During the 12th Five-Year Plan period (2011–2015), significant decoupling between agricultural, industrial, commercial, and ecological LUEs and CEs was observed in 170 (59%), 119 (42%), 117 (41%), and 139 (49%) cities, respectively. (3) From a long-term perspective (2010–2019), all types of LUE and CEs that were initially absent in geographic agglomeration showed improvement and achieved decoupling. (4) The initial set of low-carbon pilot cities that aimed to reduce CEs showed the most success, but this advantage faded with time. Our research delves into the interactions of actors with land resources and their implications for CEs within the SES framework. Through exploring the decoupling of LUE and CEs, we provide valuable insights for actors to make strategic adjustments, enhancing societal resilience and promoting harmonious development between humans and nature in the social-ecological system.

Rapid identification of bacteria in water by multi-wavelength transmittance spectroscopy and the artificial neural network

Background: Multi-wavelength transmittance spectroscopy, in combination with the artificial neural network, has been a novel tool used to identify and classify microorganisms in recent years.Methods: In our work, the transmittance spectra in the region from 200 to 900 nm for four bacterial species of interest, Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Klebsiella pneumoniae (K.pneumoniae), and Salmonella typhimurium (S. typhi), were recorded using an ultraviolet–visible spectrophotometer. Considering too much redundant data on the full-wave band spectra, the characteristic wavelength variables were selected using the competitive adaptive reweighting sampling (CARS) algorithm. Spectra of the initial training set of these targeted microorganisms were used to create identification models representing the spectral variability of each species using four kinds of neural networks, namely, backpropagation (BP), radial basis function network (RBF), generalized regression neural network (GRNN), and probabilistic neural network (PNN).Results: The blinded isolate spectra of targeted species were identified using the four identification models given above. Compared to fullband modeling, after using CARS to screen the wavelength variables, four identification models are established for the 35 preferred characteristic wavelengths, and the prediction performance of the four models is notably improved. Among them, the CARS–PNN model is the best, and the identification rates of all targeted bacteria were achieved with 100% accuracy; the calculation time is just approximately 0.04 s.Discussion: The use of CARS can effectively remove useless information from the spectra, reduce model complexity, and enhance model prediction performance. Multi-wavelength transmission spectroscopy, combined with the CARS–PNN method, can provide a new method for the rapid detection of bacteria in water and could be readily extended for bacterial microbiological detection in blood and food.

Pengelolaan Daun Kering untuk Pupuk Kompos

A material given to plants to increase nutrient availability is called fertilizer. This research project aims to find a solution to the environmental pollution problem caused by the accumulation of dry leaf litter. Compost is made using dry leaf litter waste as the main component and EM4 as an aid. EM4 is responsible for breaking down the organic material in the leaves. The finished dry leaf compost is odorless, in the form of loose granules, has a brittle and somewhat rough texture, and is dark brown in color. The research method used is literature research, or research derived from books and print journals accessible on Google Scholar. This type of research uses descriptive studies and several works of researchers with relevant fields of study. Data collected through inductive methods are then analyzed using one or more initial data sets. The obtained data is examined using a descriptive analytical approach. By transforming dry leaves into more useful and economically valuable compost, this research also aims to develop and enhance the creative abilities of the community and the local economy. Bright colors indicate composting that is too dry or moisture levels below 30%. One determining factor of compost maturity is its aroma. The compost fermentation process will produce various strong aromas.

Developing an initial set of quality indicators for chiropractic care: a scoping review

BackgroundQuality indicators are standardized, evidence-based measures of health care quality. Currently, there is no basic set of quality indicators for chiropractic care published in peer-reviewed literature. The goal of this research is to develop a preliminary set of quality indicators, measurable with administrative data.MethodsWe conducted a scoping review searching PubMed/MEDLINE, CINAHL, and Index to Chiropractic Literature databases. Eligible articles were published after 2011, in English, developing/reporting best practices and clinical guidelines specifically developed for, or directly applicable to, chiropractic care. Eligible non-peer-reviewed sources such as quality measures published by the Centers for Medicare and Medicaid Services and the Royal College of Chiropractors quality standards were also included. Following a stepwise eligibility determination process, data abstraction identified specific statements from included sources that can conceivably be measured with administrative data. Once identified, statements were transformed into potential indicators by: 1) Generating a brief title and description; 2) Documenting a source; 3) Developing a metric; and 4) Assigning a Donabedian category (structure, process, outcome). Draft indicators then traversed a 5-step assessment: 1) Describes a narrowly defined structure, process, or outcome; 2) Quantitative data can conceivably be available; 3) Performance is achievable; 4) Metric is relevant; 5) Data are obtainable within reasonable time limits. Indicators meeting all criteria were included in the final set.ResultsLiterature searching revealed 2562 articles. After removing duplicates and conducting eligibility determination, 18 remained. Most were clinical guidelines (n = 10) and best practice recommendations (n = 6), with 1 consensus and 1 clinical standards development study. Data abstraction and transformation produced 204 draft quality indicators. Of those, 57 did not meet 1 or more assessment criteria. After removing duplicates, 70 distinct indicators remained. Most indicators matched the Donabedian category of process (n = 35), with 31 structure and 4 outcome indicators. No sources were identified to support indicator development from patient perspectives.ConclusionsThis article proposes a preliminary set of 70 quality indicators for chiropractic care, theoretically measurable with administrative data and largely obtained from electronic health records. Future research should assess feasibility, achieve stakeholder consensus, develop additional indicators including those considering patient perspectives, and study relationships with clinical outcomes.Trial registrationOpen Science Framework, https://osf.io/t7kgm

Multi-effect of fineness and replacement ratio of binders on thixotropic and some fresh state properties of cementitious systems, a comparative study

Effects of cement fineness, fly ash replacement ratio and fineness changes on some fresh state and rheological properties of mixtures were investigated in this study. Two different Blaine finenesses of portland cement (4000, 5000 cm2/g) and 4 different finenesses of fly ash (4000, 5000, 6000 and 7000 cm2/g) were used. 26 different paste mixtures were prepared by substituting fly ash in 3 different ratios (10%, 20%, and 30%) by weight. Marsh-funnel flow time, mini-slump, setting time, dynamic yield stress (DYS), viscosity and thixotropic behavior of mixtures were investigated. 4 different thixotropy measurement methods were used; dynamic yield stress ratio (DYSR), viscosity ratio (VR), shear stress-structural build-up area (SBUshr) and viscosity-structural build-up area (SBUvis). There was no notable change in the initial setting time results of the mixtures with the increase in portland cement fineness. The rheological parameters and thixotropic behavior of the mixtures increased significantly. Vicat-water requirement and setting-time-value decreased with the increase of fly ash fineness in cementitious mixtures with low fineness. The structural build-up of the mixtures decrease with the rise of the F class FA replacement ratio. It was determined that the methods with the highest correlation among thixotropy measurement methods were SBUshr-SBUvis, DYSR-SBUshr and DYSR-Athix, respectively.

Does the injury pattern drive the surgical treatment strategy in multiply injured patients with major fractures?

The timing of definitive surgery in multiple injured patients remains a topic of debate, and multiple concepts have been described. Although these included injury severity as a criterion to decide on the indications for surgery, none of them considered the influence of injury distributions. We analyzed whether injury distribution is associated with certain surgical strategies and related outcomes in a cohort of patients treated according to principles of early and safe fixation strategies. In this retrospective cohort study, multiple injured patients were included if they were primarily admitted to a Level I trauma center, had an Injury Severity Score of ≥16 points, and required surgical intervention for major injuries and fractures. The primary outcome measure was treatment strategy. The treatment strategy was classified according to the timing of definitive surgery after injury: early total care (ETC, <24 hours), safe definitive surgery (SDS, <48 hours), and damage control (DC, >48 hours). Statistics included univariate and multivariate analyses of mortality and the association of injury distributions and surgical tactics. Between January 1, 2016, and December 31, 2022, 1,471 patients were included (mean ± SD age, 55.6 ± 20.4 years; mean Injury Severity Score, 23.1 ± 11.4). The group distribution was as follows: ETC, n = 85 (5.8%); SDS, n = 665 (45.2%); and DC, n = 721 (49.0%); mortality was 22.4% in ETC, 16.1% in SDS, and 39.7% in DC. Severe nonlethal abdominal injuries (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.4-3.5) and spinal injuries (OR, 1.6; 95% CI, 1.2-2.2) were associated with ETC, while multiple extremity injuries were associated with SDS (OR, 1.7; 95% CI, 1.4-2.2). Severe traumatic brain injury was associated with DC (OR, 1.3; 95% CI, 1.1-1.4). When a correction for the severity of head, abdominal, spinal, and extremity injuries, as well as differences in the values of admission pathophysiologic parameters were undertaken, the mortality was 30% lower in the SDS group when compared with the DC group (OR, 0.3; 95% CI, 0.2-0.4). Major spinal injuries and certain abdominal injuries, if identified as nonlethal, trigger definitive surgeries in the initial setting. In contrast, severe TBI was associated with delayed fracture care. Patients with major fractures and other injuries were treated by SDS (definitive care, <48 hours) when the pathophysiological response was adequate. The choice of a favorable surgical treatment appears to depend on injury patterns and physiological patient responses. Therapeutic/Care Management; Level IV.

Low-Order Automatic Domain Splitting Approach for Nonlinear Uncertainty Mapping

This paper introduces a novel method for the automatic detection and handling of nonlinearities in a generic transformation. A nonlinearity index that exploits second-order Taylor expansions and polynomial bounding techniques is first introduced to estimate the Jacobian variation of a nonlinear transformation. This index is then embedded into a low-order automatic domain splitting algorithm that accurately describes the mapping of an initial uncertainty set through a generic nonlinear transformation by splitting the domain whenever nonlinearities grow above a predefined threshold. The algorithm is illustrated in the critical case of orbital uncertainty propagation, and it is coupled with a tailored merging process that limits the growth of the domains in time by recombining them when nonlinearities decrease. The low-order automatic domain splitting algorithm is then combined with Gaussian mixture models to accurately describe the propagation of a probability density function.

Morphofunctional and psychophysiological body indicators in monitoring students’ health status, in view of their adjustment to academic environment

Students’ adjustment to higher education process depends largely on the body’s individual features. The student’s physiological and psychological status, as well as the initial motivational setting attitudes are the determining factors. Given this backcloth, the search for ways to improve the health, while aiming at enhancing future qualified specialists’ working and adjustment capacity, appears to be an issue of utmost importance.Material and methods. A longitudinal study involving university students of different years was carried out, through which anthropometric data were evaluated for the same students in their 1st year and then – in their 2nd year of training; the concentration of testosterone and cortisol in saliva, thyroid-stimulating hormone and triiodothyronine in blood serum was measured by ELISA; also, psychophysiological values were estimated through unified questionnaires.Results. The results showed that over the course of education, the students had their hemoglobin concentration, average hemoglobin content in erythrocytes, and leukocyte number decreased. Notable was a significant increase in 3rd year students’ thyroid-stimulating hormone content and a decrease of triiodothyronine and testosterone. A test relying on the Buss – Durkee Hostility Inventory helped to detect an increase in the aggression and suspicion criterion indicators among senior students if matched versus similar values obtained for their freshmen-counterparts.Conclusions. The research outcomes expand the informational and the methodological base required to evaluate an average student’s functional status from the standpoint of a systematic approach and the theory of the norm. Besides, such data will offer an insight into the main mechanisms behind stressinducing, just like stress-limiting, adjustment strategies. This study of the morphofunctional status indicators allows – while within the annual health monitoring approach – identifying the regulatory and the adjustment capacities in students, both at the time they are enrolled as freshmen and further, thus helping predict the potential risk of maladjustment, which, in turn, may serve a useful tool in taking preventive measures, the final goal being to maintain students’ health through their higher education training period.

Improvement on engineering properties and volumetric stability of alkali-activated slag-based composite cementitious material with rice husk ash and magnesium oxide

This study used rice husk ash (RHA) and magnesium oxide (MgO) to improve the engineering properties and volumetric stability of alkali-activated slag-based cementitious material. Experimental results found that when the amount of slag substituted by RHA increased from 0% to 20%, the initial setting time was extended from 15 to 20 min, and the final setting time was shortened from 35 to 30 min for the paste without MgO. The optimal substitution amount of RHA was 10%, which had the maximum compressive strengths at ages of 28 and 56 days to achieve 104.44 and 102.43 MPa for the paste without MgO, respectively. The drying shrinkage of paste without MgO increased with both the increase of RHA from 0% to 20% and ages from 3 to 56 days. With RHA, the drying shrinkage substantially decreased with the substitutions of MgO from 0% to 2.0% and almost remained steady after ages of 7 or 14 days. The optimal amount of RHA to replace slag was less than 10% and the optimal content of MgO was less than 1%, which can effectively improve the volumetric stability and reduce the heat of hydration of paste.