Changes In Dynamic Parameters Research Articles

ВЛИЯНИЕ РОСТА СКЕЛЕТНО-МЫШЕЧНОЙ МАССЫ НА ПОКАЗАТЕЛИ ОБМЕНА ЖЕЛЕЗА У ВОЕННОСЛУЖАЩИХ ПО ПРИЗЫВУ В ПЕРИОД АДАПТАЦИИ К УСЛОВИЯМ ВОЕННОЙ СЛУЖБЫ

Thousands of young men are conscripted for military service with various nutritional status and physical fitness condition every year. The adaptation of conscripted soldiers to the factors of military service occurs at three levels: physiological, psychological and social. The purpose of the study was to assess the dynamic changes of body structure parameters in conscripted soldiers during 6 months of service by conscription and to determine the effect of skeletal muscle mass growth on iron metabolism during adaptation to military service conditions. A prospective observational study involved 145 conscripted soldiers from one of the military units after informed consent. The study was performed from the moment of conscription for military service in 3 stages with an interval of 3 months using a four-component model of body structure and a four-component model of iron metabolism. The skeletal muscle mass and adipose tissue mass and were determined caliperometrically. Hematological and biochemical parameters of iron metabolism were assessed. Dynamic changes and types of growth of the skeletal muscle mass, as well as changes in the parameters of iron metabolism have been obtained. The body weight of conscripted soldiers changes slightly within 6 months from the moment of conscription. At the same time internal changes occurred in the structure of the body of conscripted soldiers due to an increase in skeletal muscle mass and a decrease in the mass of adipose tissues. The types of skeletal muscle mass growth were determined among conscripted soldiers. There were an increase in skeletal muscle mass and hemoglobin fund to provide them oxygen by the influence of increased physical loading. It led to a decrease in iron stores, estimated by serum ferritin, and signs became more pronounced of iron deficiency erythropoiesis, which were determined in erythrocyte indexes. These combined changes can be assessed as functional iron deficiency or iron deficiency without anemia.

Online assessment of failure probability for smart meters based on SARIMA-LTFRLS

• An adaptive time-varying forgetting-factor based on the fuzzy control principle is proposed for the first time, which can balance the stability and convergence speed of identification, thus ensuring the real-time prediction of SARIMA. • The limited memory principle is introduced into the identification process to keep the amount of BE data used for recursion fixed, and then a new LTFRLS which can well track the dynamic change of parameters in SARIMA is presented. • A new FP online assessment framework for SMs is given by combining SARIMA and LTFRLS, which combines the failure thresholds of BE and its future predictions to evaluate the running state of instruments. Online assessment of the failure probability (FP) for smart meters (SMs) is crucial for accurately measuring the electrical energy of instruments and judging their operation state. Basic error (BE) is the main performance parameter of SMs, and its trend and seasonality can be well described by the seasonal autoregressive integrated moving average (SARIMA) model. However, when the BE data increase online, the static SARIMA can't quickly and accurately reflect the dynamic performance of SMs. To this end, a limited-memory time-varying forgetting-factor recursive least squares (LTFRLS) algorithm for real-time updating of parameters in SARIMA is proposed for the first time, and a new FP online prediction framework is constructed by combining it with SARIMA. Firstly, an adaptive time-varying forgetting-factor (TF) based on the fuzzy control theory is presented to dynamically adjust the forgetting factor in LTFRLS. Next, the limited memory principle is introduced to keep the amount of BE data involved in identification iteration unchanged, thereby overcoming data saturation. Actual datasets from three companies show that LTFRLS has good recognition accuracy, fast convergence speed, and versatility. Compared with several others, SARIMA-LTFRLS can realize online prediction of BE, which is more effective for the state prediction of SMs.

Constructions of the experimental-estimation model for releasing combustion products at thermal pulse processing

The object of this study are ways to ensure the speed and repeatability of the valve for the release of combustion products from the thermal-pulse unit, which are the most important parameters that enable the precision of the finishing treatment with detonating gas mixtures. The study is aimed at analyzing the process of releasing combustion products in the valve of the proposed design; identification of factors that affect the speed of its opening; establishing the nature of the change in gas dynamic parameters in the combustion chamber. Experimental studies were carried out on a specialized bench simulating the operation of a valve with pressure measurement in gas cavities and controlling the movement of a movable glass of the valve with an incremental encoder. Information on the position of the movable cup is obtained in real time with a decisive ability of 3 microns. The experimental study showed that an increase in the response rate of the valve of the design under consideration to the values required for precision thermal pulse treatment (0.01 s) is possible subject to the use of compressed air. To study the flow processes of high-temperature gases during the operation of the controlled outlet valve, partially immersed in water, a numerical model has been built. A feature of the model is to take into account the real values of the friction force acting on the moving part of the valve, due to the introduction of resistance force acting on the movable glass. The magnitude of this force under the specified initial conditions is assigned from the condition of ensuring the coincidence between the estimated opening time of the valve and its average value obtained from full-scale experiments. For the range of design conditions, based on the lower limit of the working pressure of the combustion products, the water level is determined in the chamber of the thermal pulse equipment, on which the valve must be partially immersed for safe operation

A unified approach for dynamic characteristic analysis of a standing-wave thermoacoustic engine with general impedance ends

As promising devices for energy conversion, thermoacoustic engines (TAEs) are attracting more and more research attention with regard to renewable thermal energy application. For a TAE, the oscillation frequency is a critical parameter in its design and operation, which can only be estimated currently through an often tedious process using a shooting method or a numerical iteration method, and an analysis model with classical boundary conditions. In this context, this study seeks to establish a unified model for dynamic analysis of a one-dimensional (1D) standing-wave TAE with general impedance ends. First, the differential equations governing the thermoacoustic behavior of the TAE and its impedance boundary conditions are simultaneously solved using the Galerkin method and an improved Fourier series expansion method. Then, the characteristic distributions of oscillation frequency, sound pressure, and volume flow rate are obtained by solving a standard eigenvalue problem. Finally, the effects of engine length, stack length and position, and impedance ends on the dynamic behavior of the TAE’s thermoacoustic system are investigated and analyzed. The results show that engine length has a significantly negative correlation with the modal frequencies in different working gases, and stack position and stack length have a slight effect on the oscillation frequency of the TAE. The arbitrary variations in impedance boundary conditions can be simulated from the open end to the rigid wall and all intermediate cases. The proposed model can efficiently predict changes in dynamic parameters of 1-D TAEs with impedance ends in a unified pattern and can serve as a reliable analysis tool for further research on TAEs coupled with various energy harvesters.

Free vibration analysis and prediction modeling of delaminated tapered FRP composite plates

Delamination (the separation between plies) is a common failure in Fiber Reinforced Polymer (FRP) laminated composites. The presence of delamination reduces the structural stiffness and changes in dynamic responses. The change in dynamic parameters can be successfully used for assessing structural health monitoring (SHM) for composite structures. SHM requires large amount of numerical/experimental data. This study focuses on the influence of the delamination parameters (size and in-plane location) on vibration behavior of a laminated tapered fiber reinforced polymer (FRP) composite plate with ply drop-off. Furthermore, developing a surrogate model as a fast-executing model to predict the shift in the natural frequency to reduce the computational effort for solving forward problems. The layerwise theory (LWT) has been used, and the delamination is modeled by “constrained mode” were solved using the finite element method (FEM). The numerical model was validated with an experimental modal analysis of tapered plates without delamination to make the model more robust. The effect of delamination was studied using surface plots produced using response surface methodology (RSM). The results show that the delamination size and location significantly affect the natural frequency shift. The RSM and ANN models were considered as surrogate models, and it was evaluated using an experimental modal analysis. The results shows that the single-output ANN model can predict the shift in the natural frequency with a minimum Root Mean Square Error (RMSE).

Methodology for determining parameters of design vehicle, taking into account conditions of Arctic zone of the Russian Federation

Over the past decades, the automotive market has been growing and developing rapidly. Vehicles are constantly modified: their geometric parameters (length, width, height, etc.) and dynamic parameters (power, acceleration speed, etc.) change. For the design and construction of the roadway, as well as subsequent calculations in the field of traffic management (flow saturation, mandatory control, etc.) in accordance with the regulatory documentation, geometric and dynamic parameters of the design vehicle are used, the parameters of which are determined on the basis of Soviet cars of the 80s. As a result of vehicles changes and modifications, it is necessary to update and perform additional calculations to determine the parameters of an improved design - calibrated vehicle. The main purpose of the study is to determine the parameters of the design - calibrated vehicle for performing calculations in the field of construction and traffic management. In the course of the research presented in this article, the analysis of statistical data regarding the best-selling light vehicles, as well as the variability of the geometric parameters of vehicles were determined. Based on all the completed tasks, the result of the work is determination of the design - calibrated vehicle for Arctic zone of the Russian Federation, which will be subsequently used for the design and construction of the roadway and calculations in the field of traffic management.

Effect of moisture content on the evolution of bacterial communities and organic matter degradation during bioaugmented biogas residues composting.

Composting is an excellent way to recycle biogas residues into a stable, non-toxic agricultural end product. In this study, the dynamic changes of physical-chemical parameters and bacterial community in three groups of bioaugmentation composting systems at different moisture contents (MC) of 50% (MC50), 60% (MC60) and 70% (MC70) were monitored. The differences of bacterial communities in composts with different initial MC were compared, and the interaction between biological and non-biological parameters was also explored. The results revealed that after 30days of composting, the biogas residues compost in MC60 reached highest temperature of 64°C, total Kjeldahl nitrogen (TKN) of 2%, seed germination index (GI) of 110%, and the longest thermophilic period duration of 5days (55°C). Additionally, the result of high-throughput sequencing showed that the diversity of bacterial communities in MC60 was the highest, and the abundance of Actinobacteria (16.93-52.63%), Firmicutes (8.71-56.75%), and Proteobacteria (16.88-46.95%) in all groups were the highest at phylum level. The LEfSe analysis indicated that the abundance of Ochrobactrum and Cellulomonadaceae in MC60 was significantly (p < 0.05) higher than with other treatments. Moreover, canonical correspondence analysis (CCA) indicated thermophilic period duration is significantly (p < 0.05) positively correlated with Paenibacillus. Besides, it was found the relative abundance of Nocardiopsis and Georgenia has a significant (p < 0.01) correlation with the fertilizer efficiency of compost. These results showed that controlling the initial moisture content at 60% can improve the maturity and fertilizer efficiency of compost, and enable the bacteria beneficial to composting to gain the advantage of proliferation.

Remote Sensing of Chlorophyll-a in Xinkai Lake Using Machine Learning and GF-6 WFV Images

Lake ecosystem eutrophication is a crucial water quality issue that can be efficiently monitored with remote sensing. GF-6 WFV with a high spatial and temporal resolution provides a comprehensive record of the dynamic changes in water quality parameters in a lake. In this study, based on GF-6 WFV images and the field sampling data of Xingkai Lake from 2020 to 2021, the accuracy of three machine learning models (RF: random forest; SVR: support vector regression; and BPNN: back propagation neural network) was compared by considering 11 combinations of surface reflectance in different wavebands as input variables for machine learning. We mapped the spatiotemporal variations of Chl-a concentrations in Xingkai Lake from 20192021 and integrated machine learning algorithms to demonstrate that RF obtained a better degree of derived-fitting (Calibration: N = 82, RMSE = 0.82 μg/L, MAE = 0.57 μg/L, slope = 0.94, and R2 = 0.98; Validation: N = 40, RMSE = 2.12 μg/L, MAE = 1.58 μg/L, slope = 0.91, R2 = 0.89, and RPD = 2.98). The interannual variation from 2019 to 2021 showed that the Chl-a concentration in Xingkai Lake was low from June to July, while maximum values were observed from October to November, thus showing significant seasonal differences. Spatial distribution showed that Chl-a concentrations were higher in Xiao Xingkai Lake than in Da Xingkai Lake. Nutrient inputs (N, P) and other environmental factors such as high temperature could have an impact on the spatial and temporal distribution characteristics of Chl-a, therefore, combining GF-6 WFV satellite images with RF could realize large-scale monitoring and be more effective. Our results showed that remote-sensing-based machine learning algorithms provided an effective method to monitor lake eutrophication as well as technical support and methodological reference for inland lake water quality parameter inversion.

Bulk and confined acetonitrile in mesoporous silica matrices by extrinsic probing via ESR technique: Effects of pore topology, pore size and pore surface composition

The spectral behavior of the spin probe 2,2,6,6-tetramethyl-1‑piperidinyloxy (TEMPO) in acetonitrile (ACN) as arepresentative of aprotic polar medium in the bulk and in 2D-confined states of three silica matrices differing in the pore topology, pore size and pore wall composition using electron spin resonance (ESR) is presented. The changes in interaction and dynamic parameters of TEMPO due to spatial restriction of ACN and pore surface chemistry are related to phase behaviors from differential scanning calorimetry (DSC). The obtained ESR findings are compared with those for apolar and protic polar media in the same native and modified confining silica matrices.

Effects of Intercropping of Sophora davidii (Franch.) Skeels and Pennisetum sinese Roxb on Soil Physical and Chemical Properties and Fungal Communities in Rhizosphere

The intercropping treatment has been widely used to improve the crop productivity and achieve the development of efficient agricultural practice. In this study, to further explore the effect of Gramineae and Leguminosae intercropping, Sophora davidii (Franch.) Skeels and Pennisetum sinese Roxb under monoculture and intercropping were performed, the rhizosphere soil was collected, the physical and chemical properties (pH, AP, AK), enzyme activities (βG, LAP, NAG and AcP) and fungal community diversity were tested. In the results, intercropping changed the physical and chemical properties and enzyme activities of rhizosphere soil. Compared with the monoculture, intercropping decreased the α-diversity of soil fungal communities. At the phylum level, intercropping significantly increased the relative abundance of Ascomycota and Ciliophora, while decreased the relative abundance of Mucoromycota and Chytridiomycota, compared with monoculture. At the genus level, the relative abundances of Fusarium, Talaromyces, Preussia, Mycoleptodiscus, Plectosphaerella and Bracteacoccus in intercropping were higher than those under monoculture, while the relative abundances of Lablab, Aspergillus and Rumex were lower. RDA analysis showed that, soil fungal community structure was mainly affected by soil enzyme activity under intercropping system. In conclusion, the soil fungal community depends largely on management measures of monoculture and intercropping, compared with the dynamic changes in soil environmental parameters. This study can provide a reference for the assessment of soil ecological effect of intercropping.

Water-lifting and aeration system improves water quality of drinking water reservoirs: Biological mechanism and field application

Reservoirs have been served as the major source of drinking water for dozens of years. The water quality safety of large and medium reservoirs increasingly becomes the focus of public concern. Field test has proved that water-lifting and aeration system (WLAS) is a piece of effective equipment for in situ control and improvement of water quality. However, its intrinsic bioremediation mechanism, especially for nitrogen removal, still lacks in-depth investigation. Hence, the dynamic changes in water quality parameters, carbon source metabolism, species compositions and co-occurrence patterns of microbial communities were systematically studied in Jinpen Reservoir within a whole WLAS running cycle. The WLAS operation could efficiently reduce organic carbon (19.77%), nitrogen (21.55%) and phosphorus (65.60%), respectively. Biolog analysis revealed that the microbial metabolic capacities were enhanced via WLAS operation, especially in bottom water. High-throughput sequencing demonstrated that WLAS operation altered the diversity and distributions of microbial communities in the source water. The most dominant genus accountable for aerobic denitrification was identified as Dechloromonas. Furthermore, network analysis revealed that microorganisms interacted more closely through WLAS operation. Oxidation-reduction potential (ORP) and total nitrogen (TN) were regarded as the two main physicochemical parameters influencing microbial community structures, as confirmed by redundancy analysis (RDA) and Mantel test. Overall, the results will provide a scientific basis and an effective way for strengthening the in-situ bioremediation of micro-polluted source water.

Heparin therapy in COVID-19: Call for randomized controlled trials (RCTs).

Coronavirus disease 2019 (COVID-19) is associated with increases in abnormal coagulation, and particularly D-dimer (D-D) levels. Heparin therapy has been recommended as pharmacologic thromboprophylaxis in patients hospitalized with COVID-19; however, data on its efficacy are lacking. The current study retrospectively analyzed changes in blood coagulation and the impact of heparin therapy. Medical records of 593 patients with confirmed COVID-19 were collected. On admission, elevated fibrinogen (Fg) levels were noted in with 42.2% (250/593) of patients, followed by increases in D-D (28.5%) and a prolonged prothrombin time (PT) (23.9%). Patients with severe/critical COVID-19 had a higher proportion of abnormal coagulation parameters than patients with mild/ordinary COVID-19. Dynamic changes in coagulation parameters were plotted on timeline charts for 97 patients with COVID-19 after heparin treatment. These changes, when combined with Fg, PT, D-D, and other indicators, may provide a relatively comprehensive description of coagulation abnormalities. Heparin seems to be important in the treatment of patients with COVID-19 based on the current findings. The efficacy of heparin in the treatment of COVID-19 should be confirmed by randomized controlled trials (RCTs) as soon as possible.

Succession changes of fermentation parameters, nutrient components and bacterial community of sorghum stalk silage.

To better understand the ensiling characteristics of sorghum stalk, the dynamic changes of fermentation parameters, nutrient components and bacterial community of sorghum stalk silage were analyzed by intermittently sampling on day 0, 1, 3, 7, 14, 28, and 56 of ensiling duration. The results showed that high-moisture sorghum stalk was well preserved during ensiling fermentation, with the DM loss of 4.10% and the little difference between the nutrients of sorghum stalk before and after ensiling. The pH value of silage declined to its lowest value of 4.32 by Day 7 of ensiling, and other fermentation parameters kept steady since Day 28 of ensiling. The amplicon sequencing analysis revealed that the alpha diversity parameters of silage bacterial community including Shannon index, observed features, Pielou evenness and Faith PD gradually declined (P < 0.01) with ensiling duration. Principal coordinate analysis (PCoA) revealed that bacterial profiles of raw material would experience a succession becoming a quite different community during ensiling fermentation. Taxonomic classification revealed a total of 10 and 173 bacterial taxa at the phylum and genus level, respectively, as being detected with relative abundances higher than 0.01% and in at least half samples. LEfSe analysis revealed that 26 bacterial taxa were affected by sampling timepoint (P < 0.05 and LDA score > 4). When focusing on the dynamic trend of silage bacterial taxa, lactic acid bacteria successfully dominated in the bacterial community on Day 1 of ensiling, and the bacterial community almost came to a plateau by Day 28 of ensiling, with Lactobacillus and Leuconostoc as the dominant genera. In a word, the succession of fermentation parameters, nutrient components and bacterial community indicate a successful dominance establishment of LAB and a fast advent of fermentation plateau, suggesting that high-moisture sorghum stalk can be ensiled directly, but the pH of mature silage is a little high.

A digital twin-driven trajectory tracking control method of a lower-limb exoskeleton

A direct drive motor is the main component for tracking the gait rehabilitation training trajectory of a lower-limb exoskeleton (LLE). Aiming at the movement instability caused by the changes in the moment of inertia and assembly characteristics of the LLE, a trajectory tracking control method based on the digital twin model is proposed in the study. Firstly, the key characteristic parameters of LLE driven by the direct drive motor are extracted to establish a virtual twin model of LLE. Secondly, the digital twin model is driven by the physical-entity state data and the control parameters of the motor servo are optimized through the twin model based on an adaptive feedback control strategy. Finally, in order to improve the real-time feedback accuracy between the twin model and the physical entity, with the depth deterministic policy gradient and particle swarm optimization algorithm (DDPG-PSO), the parameter matching error between the twin model and the physical entity is reduced. In this way, a digital twin-driven compound control algorithm is obtained. In addition, the proposed method was verified through three sets of experiments. In Experiment 1, the virtual joint angle trajectory θfic of the twin model was compared with the actual joint angle trajectory θact and the average error was no more than 0.05, indicating that the twin model could accurately restore the motion trajectory of the physical entity. In Experiment 2, by comparing with tracking effects of Model-free adaptive control, the adaptive feedback control of digital twin-driven has better stability, and can effectively resist external interference. In Experiment 3, under the no-load condition, the algorithm converged to the optimal solution after 40 iterations. In addition, dynamic parameter changes could be detected in real time, thus proving the rapid convergence and good performance of the DDPG-PSO algorithm.

GAN-based Technology of Generating Spoofing-jamming I/Q Signal

&lt;p&gt;The existing wireless communication interference methods rely heavily on the characteristics of the target signals obtained in communication reconnaissance, require complex prior knowledge, and have problems in keeping up with the dynamic changes of relevant parameters. This paper proposes a GAN-based tech-nology of generating spoofing-jamming I/Q signals. The jammer will be able to deceive and interfere with op-ponents through GAN by generating spoofing-jamming I/Q signals highly correlated to real I/Q signals without prior knowledge. This paper first introduces the principle of GAN and the GAN model to be adopted; uses a software radio system composed of LabView and NI USRP software and hardware plat-forms to simulate real communication scenarios to collect real I/Q signal data; generates spoofing-jamming I/Q signals through GAN model; uses t-SNE algorithm to perform dimensionality reduction on both the real and the spoofing-jamming I/Q signal data to visualize their distributions; finally, tests the spoofing-jamming I/Q signals on receiver’s pre-trained classifier. The experimental results show that GAN provides an effective method for generating high-quality spoofing-jamming I/Q signals.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Vitamin D levels and clinical outcomes of SARS-CoV-2 Omicron subvariant BA.2 in children: A longitudinal cohort study.

ObjectiveTo investigate the picture between vitamin D levels and clinical outcomes of SARS-CoV-2 Omicron subvariant BA.2 in children.MethodsA retrospective, longitudinal cohort study was performed. All included hospitalized cases were divided into the sufficient (sVD) and insufficient vitamin D (iVD) groups according to whether their serum 25-hydroxyvitamin D [25(OH)D] concentration was ≥30 ng/mL. Dynamic changes in clinical parameters were observed for seven time periods within 28 days after admission.ResultsSerum 25(OH)D concentrations were significantly negatively correlated with age in the included cases (r = −0.6; P < 0.001). Compared with the iVD group (n = 80), the sVD group (n = 36) had higher interleukin-6 (18.4 vs. 12.9; P = 0.003) within the first day; higher procalcitonin within the first (0.15 vs. 0.1; P = 0.03), 2–3 (0.14 vs. 0.07; P = 0.03), 4–5 (0.21 vs. 0.07; P = 0.02) days; more lymphocytes within the first (1.6 vs. 1.2; P = 0.02), 2–3 (3.7 vs. 2; P = 0.001), 4–5 (3.9 vs. 2.1; P = 0.01) and 6–7 (4.9 vs. 2.7; P = 0.02) days; notably, higher cycle threshold for N gene (30.6 vs 19.8; P = 0.03) or ORF1ab gene (31.4 vs 20.1; P = 0.03) within 2 to 3 days. Pneumonia lesions were found in eleven and six cases in the iVD and sVD groups, respectively, without significant difference on computed tomography at admission. Six out of eleven and five out of six had a repeat computed tomography after 1–2 weeks. Lesion improvement was more significant in the sVD group (P = 0.04).ConclusionsChildren with vitamin D insufficiency might have poorer clinical outcomes in Omicron subvariant BA.2 infection, especially in older pediatric patients. Further studies are needed to assess effectiveness of supplements in reducing the same.

Evaluation of dynamic spinal alignment changes and compensation using three-dimensional gait motion analysis for dropped head syndrome

BACKGROUND CONTEXTDynamic kinematic evaluation of spino-pelvic alignment during gait using three-dimensional (3D) motion analysis has been proposed for adult spinal thoracolumbar deformity. That is because conventional full-spine radiographs cannot be used to evaluate dynamic factors. However, dynamic changes in spino-pelvic alignment during gait for dropped head syndrome (DHS) have not been studied using this approach. PURPOSE: This study aimed to assess the dynamic changes in spinal-pelvic alignment during gait in patients with DHS using 3D motion analysis. STUDY DESIGNRetrospective review of collected radiographic and kinematic data. PATIENT SAMPLENineteen DHS patients with neck pain and/or anterior gaze disturbance. OUTCOME MEASURESStatic spino-pelvic radiological alignment, dynamic spino-pelvic kinematic parameters and electromyogram (EMG) data. METHODSCenter of gravity of the head - C7 sagittal vertical axis (CGH-C7 SVA), C2-C7 SVA, T1 slope; cervical lordosis (CL), C7SVA, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT) and pelvic incidence (PI) were assessed using full-spine radiographs in a standing position to assess static spino-pelvic alignment. The 3D gait motion analysis was conducted during gait. Dynamic kinematic parameters were divided into spinal segments: cervical (C-), thoracic (T-), lumbar (L-) and pelvis (P-). Each spinal segment coronal angle to the pelvic angle, each spinal segment sagittal angle to the pelvic angle and pelvic sagittal angle to the horizontal axis were assessed as dynamic spino-pelvic kinematic parameters. Trunk and lower limb muscle activity during gait were assessed using wireless surface EMG analysis. Dynamic spino-pelvic kinematic variables and muscle activity were compared between the first walking lap and the final lap during gait analysis. The change in dynamic kinematic parameters was correlated with static radiological alignment and electromyographic muscular activity change. RESULTSCervical and thoracic anterior tilt increased significantly after an extended period of walking, indicating that dropped head worsened during gait. An increase of cervical anterior tilt during walking was significantly associated with decreased muscle activity in the cervical paraspinal muscles (r=-0.463, P<.05) and latissimus dorsi (r=-0.763, p<.01). Furthermore, significant correlations were found between a change in thoracic sagittal angle to pelvic angle and C7SVA (r=0.683, p<.01) and LL (r=-0.475, p<.05). This means that a larger C7SVA and smaller LL were associated with increased thoracic anterior tilt during gait. CONCLUSIONSThe 3D motion analysis for DHS showed that cervical and thoracic anterior tilt significantly increased after extended walking, resulting in worsening of dropped head. Decreased muscle activity of the neck extensor muscles during gait suggests insufficient neck extensor muscle endurance, which was associated with increased cervical anterior tilt. A greater increase in the thoracic anterior tilt during gait was found in DHS patients with a larger C7SVA and smaller LL due to insufficient thoracolumbar compensation for the dropped head. Correction of the cervical spine alone would not be sufficient to improve dropped head in cases with increased thoracic anterior tilt during gait. The results suggest that C7SVA and LL are crucial parameters in the surgical strategy for DHS.

Experimental research on damage identification of topping dangerous rock structural surface based on dynamic characteristic parameters

Rock block tilting is one of the most common types of dangerous rock block failures with no clear indicator of displacement prior to failure. Existing stability evaluation methods remain limited in their ability to constrain the non-penetrating section area, which is closely related to rock stability, and stability evaluations are therefore associated with large uncertainties. The dynamic characteristic parameters of toppling dangerous rock are closely related to structural plane strength. Under vibration loading, rainfall, and/or excavation unloading conditions, the structural plane becomes damaged and the dynamic characteristic parameters change. In this study, we present a dynamic characteristic model of rock tilting and identify the quantitative and qualitative relationship between dynamic characteristic parameters and the bonded area of the structural plane. The model accuracy is verified by experiments. The experimental results show that the damping ratio decreases linearly with structural plane damage, whereas the maximum vibration speed and particle trajectory increases nonlinearly and the natural vibration frequency decreases nonlinearly. The dynamic characteristic model and experimental results can be used to evaluate the degree of structural surface damage of toppling dangerous rock.

Экспериментальное исследование динамических характеристик трубопровода гидромеханической системы

The article considers vibration resistance of hydromechanical system pipelines characterizing the reliability of their operation. As a rule, vibrations and noise in pipelines are caused by pressure pulsations in the flow of the working medium and structural vibrations from superchargers propagating along the pipeline structure. An experimental analysis of vibroacoustic parameters of a real complex pipeline system with a supercharger was performed to study its dynamic behavior. At this stage of the study, the stationary process of pump operation forming a turbulent flow in the pipeline, was researched. In the course of the physical experiment, a spectral analysis was performed and vibroacoustic spectra were built at the selected control points of a separate straight section of the pipeline in the frequency range of 0.5 ... 400.0 Hz. An analysis of the change in dynamic parameters along the length of a straight section was made at various flow rates of the working fluid. The influence of the operating parameters of the supercharger (supply and pressure) on the vibroacoustic characteristics of the pipeline was studied. It was found that transverse oscillations are of greater importance in the formation of the dynamic behavior of the studied area. It is determined that with increasing the flow rate, the relative vibrational displacement of the pipeline along the X axis (longitudinal vibrations) also increases.

Effect of starter cultures on dynamics succession of microbial communities, physicochemical parameters, enzyme activities, tastes and volatile flavor compounds during sufu fermentation

This study was to investigate dynamic changes of microbial communities, physicochemical parameters, enzyme activities, tastes and volatile flavor compounds of sufu fermented by different starters during sufu fermentation. The results showed that sufu inoculated starter cultures B (MSC-B) consisted of Rhizopus oligosporus, Mucor 40,899, Saccharomyces cerevisiae and Lactobacillus bulgaricus with a ratio of 4:2:2:1 had higher contents of soluble protein and amino nitrogen as well as superior activity of protease, glucoamylase and lipase. Correlation analysis demonstrated that the three starters were significantly positive correlated with total acid, amino acid nitrogen and soluble protein. In addition, using MSC-B to produce sufu, aspartic increased by 17.5-fold. Moreover, fruity smell and burnt sugar flavor were the key volatile flavor compounds for sufu fermented by MSC-B in the pre-fermentation. Alcohols became the predominant volatile flavor compounds in the post-fermentation for the three starter cultures. In conclusion, MSC-B is of great potential in the application of sufu industry. Our work will provide a theoretical reference for the development of new mixed - starter cultures in sufu.