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ObjectiveTo analyze and study the causes and treatment approaches for lumbar disc herniation, focusing on office workers.MethodsThe concept of spinal internal balance disorder as a foundation for treating traumatic spinal diseases was introduced. Pathological changes occurring with single (or multiple) vertebral displacement were considered. For the first time, the “spinal (point) rotation repositioning method” from traditional Chinese bone setting was combined with NMES (neuromuscular electrical stimulation) technology to treat low back pain.ResultsThe patient's symptoms of low back pain were cured within a short period, allowing a quick return to work and daily life, with no recurrence of the disease observed during long-term follow-up.ConclusionThe combination of traditional Chinese bone setting and NMES provides a more effective and quicker resolution to low back pain in office workers with lumbar disc herniation. This integrated approach not only relieves pain but also restores lumbar function, ensuring long-term stability and reducing recurrence.

The wind farm layout determines the power generation ability, and its optimization remains challenging in terms of algorithm complexity and performance. Several greedy-derived and evolutionary-derived algorithms have been proposed to solve or alleviate the layout planning problems. However, greedy algorithms are efficient in finding the optimal layout but their exploration ability is poor. In contrast, evolutionary algorithms own better global search ability but require huge computational effort to find the optimal layout. Considering that all wind turbines are deployed in the same flat area (i.e. the coordinates of each wind turbine are of dimension 2, and each dimension of all turbines has the same search range), a low-complexity grey wolf optimization technique using a 2-D encoding mechanism (GWOEM) is proposed in this work. which is low-complexity and accelerates search efficiency. The proposed GWOEM effectively combines the advantages of the greedy algorithms and the evolutionary algorithms, and improves the search efficiency while maintaining accuracy. To validate the performance of the proposed GWOEM, a comparative analysis is performed based on two wind scenarios. Simulation results show that the proposed GWOEM is competitive with other state-of-the-art techniques. Compared with TDA, ADE, ADE-GRNN, and DEEM, the average power output in the two wind scenarios considered herein increases by 44.41%, 34.45%, 34.97%, and 37.06%, respectively. In terms of execution time, GWOEM is shorter than TDA, ADE, and DEEM except for ADEGRNN which increases by 12.18%.

Utilizing panel data pertaining to green building across 333 prefecture-level administrative units in China (excluding Hong Kong, Macao, and Taiwan) during the period spanning 2008–2020, an exhaustive examination of the evolution of China’s spatial pattern in green building is conducted employing the nearest neighbor index method, spatial autocorrelation analysis method, and kernel density analysis method. Furthermore, geographic probes are employed to scrutinize the determinants influencing China’s spatial configuration of green buildings. The findings reveal that: (1) An alteration in the density distribution from a “unipolar nucleus and double sub-nuclei” configuration to a “triple polar nuclei and multiple sub-nuclei” manifestation has been discerned in the spatial agglomeration of green buildings in China, exhibiting annual growth. Additionally, the center of green building development has shifted from the northwest to the southwest. (2) Pronounced agglomerations are predominantly situated in the eastern, central, and western regions of the country. High-high agglomerations have gradually dissipated over time in the central provincial capitals of China, the Yangtze River Delta, the Pearl River Delta, and the city clusters of Beijing-Tianjin-Hebei along the eastern seaboard. The western regions manifest a concentration of low-low and low-high aggregates, with high-low agglomeration primarily observed in the provincial capitals of the western regions. (3) The spatial differentiation of green buildings in China is attributable to a multitude of variables encompassing the environment, economy, society, and policies. Among these factors, economic, social, and innovative elements exert the most significant influence on the explicable degree of spatial differentiation.

Fully developed laminar flow and heat transfer performance of V-pattern folded core sandwich structures subjected to forced convection are numerically investigated. Based on the periodic feature of folded core, a methodology to simulate the fully developed flow and heat transfer state with a few unit cells is developed. The influences of geometric parameters on the coolant flow resistance and heat transfer behaviour are evaluated. Afterwards, approximate models are established based on design to optimize the heat dissipation efficiency. Design variables considered are geometric parameters of the V-pattern folded core, while the corresponding relative density is taken as a constraint. The simulation results show that the presented methodology makes it possible to analyse the fully developed regime with less computing resources. It is found that both pressure drop and heat transfer rate increase with the tortuosity of the flow channel and the inclination of the folded core. The optimization generates a design with a mildly tortuous feature in the streamwise direction to gain a maximum of heat dissipation efficiency under the current conditions.

During the flight mission of hypersonic aircraft, severe aerodynamic heating will occur on the surface, so thermal protection system (TPS) is required to protect the load-bearing structure of the aircraft. The present paper develops an engineering software for automatic optimization of the thickness of tile-type TPS for reusable aircraft. For requirements on TPS of reusable aircraft in the reentry stage, the method of heat flow-time curve enveloping, automatic material selection, and one-dimensional unsteady heat transfer calculation for multilayer plates under thermal load conditions had been researched, an interactive engineering software had been developed. The software improves the calculation accuracy and calculation efficiency of TPS thickness optimization, and it is suitable for rapid design in the conceptual design stage of the aircraft. Finally, by an example, the function of the software is verified.

Abstract Background Potassium is a nutrient element necessary for tobacco growth. Tobacco leaves with high potassium content are elastic and tough, rich in oil. And the same time, potassium can also improve the scent and aromatic value of flue-cured tobacco by regulating the synthesis of aromatic hydrocarbons in leaves.. It is an important quality indicator for flue-cured tobacco. However, the potassium concentration in tobacco leaves in most areas of China is generally lower than the global standard for high quality tobacco. Two tobacco genotypes were grafted to each other under different potassium levels to test whether potassium content and plant growth can be improved by grafting in tobacco. Results The growth of tobacco in all treatments was inhibited under potassium starvation, and grafting significantly alleviated this potassium stress in ‘Yunyan 87’. The trends in whole plant K+ uptake and K+ transfer efficiency to the leaves corresponded to the growth results of the different grafts. The nutrient depletion test results showed that the roots of ‘Wufeng No.2’ had higher K+ absorption potential, K+ affinity, and K+ inward flow rate. K+ enrichment circles appeared at the endoderm of the root section in the energy dispersive X-ray figure, indicating that the formation of Casparian strips may be partly responsible for the lower rate of lateral movement of K+ in the roots of ‘Yunyan 87’. Gene expression analysis suggested that energy redistribution at the whole plant level might constitute one strategy for coping with potassium starvation. The feedback regulation effects between scion ‘Wufeng No.2’ and rootstock ‘Yunyan 87’ indicated that the transmission of certain signaling substances had occurred during grafting. Conclusions ‘Wufeng No.2’ tobacco rootstock grafting can increase the K+ uptake and transport efficiency of ‘Yunyan 87’ and enhance plant growth under potassium stress. The physiological mechanism of the improved performance of grafted tobacco is related to higher K+ uptake and utilization ability, improved xylem K+ loading capacity, and up-regulated expression of genes related to energy supply systems.

Protein secondary structures have been identified as the links in the physical processes of primary sequences, typically random coils, folding into functional tertiary structures that enable proteins to involve a variety of biological events in life science. Therefore, an efficient protein secondary structure predictor is of importance especially when the structure of an amino acid sequence fragment is not solved by high-resolution experiments, such as X-ray crystallography, cryo-electron microscopy, and nuclear magnetic resonance spectroscopy, which are usually time consuming and expensive. In this paper, a reductive deep learning model MLPRNN has been proposed to predict either 3-state or 8-state protein secondary structures. The prediction accuracy by the MLPRNN on the publicly available benchmark CB513 data set is comparable with those by other state-of-the-art models. More importantly, taking into account the reductive architecture, MLPRNN could be a baseline for future developments.

A folded core is a three-dimensional configuration formed by folding a flat sheet of paper. Similar to foam and honeycomb, folded cores are widely used in aerospace as the cores for sandwich structures due to their excellent mechanical properties and light structural weight. In general, the core’s configuration is heterogeneous and anisotropic, while from a macroscopic point of view it is considered homogeneous. Analytical solutions of equivalent mechanical properties are generally obtained by equivalent methods and modified by numerical simulations due to the complexity of the configuration. We can find the best combination of a core’s parameters by using analytical solutions. The faceted regular folded configuration (RFC), consisting of repetitive identical cells, can be expanded to a plane. According to the principle of equivalent load-deformation, this article investigates the equivalent mechanical properties of the V-type folded core (VFC). The analytical solutions of Ez—equivalent elastic modulus in Direction z, equivalent shear modulus in Plane xz—Gxz, and equivalent shear modulus in Plane yz—Gyz have been obtained and verified by numerical simulations. In addition, the reliability of the equivalent mechanical properties is further demonstrated by the case study. By applying the analytical solutions, the optimization process of VFC can be simplified and sped up, which is of great engineering significance to the aircraft design process.

Time reversal (TR) is regarded as a potential future transmission scheme for multi-user (MU) multiple-input single-output (MISO) ultra-wideband (UWB) communication systems. In spite of TR's good performance in MU-MISO UWB systems, it suffers from performance degradation due to spatial correlation and imperfect channel-state information. In this paper, a comprehensive performance analysis of MU-MISO UWB systems with a TR pre-filter is provided. Both spatial correlation and channel estimation errors (CEE) are taken into account in the propagation channel model, and the system performance is mainly studied in terms of its effective signal-to-interference-plus-noise ratio (SINR), channel capacity, and bit error rate. The novel closed-form expressions for the average effective SINR are derived in order to characterize the influence of propagation conditions such as channel impulse response duration, spatial correlation, and CEE on TR performance metrics. The expressions reveal more precisely to us that spatial correlation and CEE have different effects on the average power of the desired signal, inter-symbol interference, and inter-user interference. Moreover, the impacts of spatial correlation and CEE on the performance of MU-MISO TR system are thoroughly investigated. In particular, the capacity loss of MU-MISO TR system due to spatial correlation and CEE is quantified and fully discussed at the end of this paper. It is shown that high spatial correlation and CEE cause a remarkable reduction in bandwidth efficiency. Finally, all theoretical results are confirmed by numerical simulations.

Aiming to mitigate the aerodynamic heating during hypersonic re-entry, the aerothermodynamic optimization of aerospace plane airfoil leading edge is conducted. Lift-todrag ratio at landing condition is taken as a constraint to ensure the landing aerodynamic performance. First, airfoil profile is parametrically described to be more advantageous during the optimization process, and the Hicks-Henne type function is improved considering its application on the airfoil leading edge. Computational Fluid Dynamics models at hypersonic as well as landing conditions are then established and discussed. Design of Experiment technique is utilized to establish the surrogate model. Afterwards, the previously mentioned surrogate model is employed in combination with the Multi-Island Genetic Algorithm to perform the optimization procedure. NACA 0012 is taken as the baseline airfoil for case study. The results show that the peak heat flux of the optimal airfoil during hypersonic flight is reduced by 7.61% at the stagnation point, while the lift-to-drag remains almost unchanged under landing condition.

The integrated thermal protection system (ITPS) is a complicated system that addresses both mechanical and thermal considerations. An M-pattern folded core sandwich panel packed with low-density insulation material provides inherently low mass for a potential ITPS panel. Herein, we identify the most influential geometric parameters and establish a viable, computationally efficient optimization procedure. Variables considered for optimization are geometric dimensions of the ITPS, while temperature and deflection are taken as constraints. A one-dimensional (1D) thermal model based on a modified form of the rule of mixtures was established, while a three-dimensional (3D) model was adopted for linear static analyses. Parametric models were generated to facilitate a design of experiment (DOE) study, and approximate models using radial basis functions were obtained to carry out the optimization process. Sensitivity studies were first conducted to investigate the effect of geometric parameters on the ITPS responses. Then optimizations were performed for both thermal and thermal-mechanical constraints. The results show that the simplified 1D thermal model is able to predict temperature through the ITPS thickness satisfactorily. The combined optimization strategy evidently improves the computational efficiency of the design process showing it can be used for initial design of folded core ITPS.

The lift force on two nonslender delta wings with sweep angles of Λ=40 and 50°, with flags attached to the leading edge, was investigated. Substantial lift enhancement in the poststall regime of the clean wings and the stall delay were observed. With a flag, the flowfield measurements showed the reattachment of the shear layer onto the wing surface and the re-formation of the leading-edge vortex, whereas the clean wing had completely stalled flow at the same angle of attack. Over a wide range of angles of attack, mass ratios, and flag lengths, the maximum lift enhancement was attained when the dimensionless frequency of flag oscillations was in an optimal range and the flag-tip velocity had sufficient amplitude. The optimal dimensionless frequency range corresponded to the natural shear layer instabilities of the clean wing. The excitation in this range substantially increased the coherency of the separated flow due to the flag oscillations. The main mechanism of the lift increase is the excitation of the shear layer, which exhibits convective instability. This is very different from the lift enhancement mechanism on airfoils where the flags lock-in to the wake instability, which is known to have an absolute instability at the poststall angles of attack of the clean airfoil. [ABSTRACT FROM AUTHOR]

The effects of the aspect ratio, the sweep angle, and the leading-edge geometry of wings placed in a turbulent wake were investigated in wind-tunnel experiments at a chord Reynolds number of 105. The poststall lift enhancement due to the leading-edge vortex formation was studied at optimal locations in the wake. The effects of the strength of the leading-edge vortices, the ratio of the spanwise length scale of the incident vortex to the wingspan, and the degree of two-dimensionality of the wake-wing interaction were studied. The competition between the effects of the spanwise length scale of the incident wake and the strength of the leading-edge vortices determined the optimal aspect ratio, which was found to be around four. Increasing the sweep angle decreased the mean lift due to the decreased two-dimensionality of the vortex formation. Airfoils with sharp leading edge produced the strongest leading-edge vortices but further away from the wing surface, resulting in lower maximum lift. Relative to the performance in the undisturbed freestream, the increases in the stall angle and maximum lift coefficient were not significantly affected by the leading-edge shape. [ABSTRACT FROM AUTHOR]

An experimental study was performed in a water tunnel to evaluate the effects of continuous and pulsed blowing jets on the counter-rotating vortices generated by the afterbody of a slanted base cylinder. Drag reductions from continuous blowing through circular jets were found to vary significantly with direction and location, and approached 7% when blowing outboard from upstream locations on the upswept face. However, for all circular jets tested, the external power required was larger than the power saved due to the drag reduction. Jet vortices restricted shear layer development, leading to smaller afterbody vortex cores further from the surface. A high-aspect-ratio jet flap, ejecting nearly parallel to the freestream, achieved drag reductions close to 9%, equating to the net energy savings of almost 3% for the best case. Jet vortices shortened the shear layer, resulting in vortices with reduced circulation, which were displaced away from the upswept face. Pulsing the jet flap resulted in improved drag reductions and energy savings (up to around 6%) compared with the equivalent continuous blowing case at the same time-averaged jet momentum coefficient. Pulsed blowing caused an increase in vortex separation and meandering, whereas the circulation was reduced by up to 10% of that for continuous blowing. [ABSTRACT FROM AUTHOR]

Location, strength, and structure of tip and edge vortices shed from wings and bodies can be manipulated by using flow control techniques. Flow physics of these approaches involve flow separation from the edge, roll-up into the vortex, wing flow regime, vortex instabilities, vortex-vortex interactions, and vortex-turbulence interactions. Actuators include continuous and unsteady blowing as well as suction, bleed, and control surfaces, which add momentum, vorticity, and turbulence into the vortices. It is noted that actuation may have effects on more than one aspect of the flow phenomena. A comparative review of the control of delta-wing vortices, tip vortices, and afterbody vortices is presented. The delay of vortex breakdown and the promotion of flow reattachment require different considerations for slender and nonslender delta wings and may not be possible at all. Tip vortices can be controlled to increase the effective span, to generate rolling moment, to attenuate wing rock, and to attenuate vortex-wing interactions. Although there are different approaches for each application, opportunities for future research on turbulence ingestion, bleed, and excitation of vortex instabilities exist. Recent research also indicates that active and passive flow control can be used to manipulate the afterbody vortices to reduce the drag. [ABSTRACT FROM AUTHOR]

An investigation of symmetry breaking and naturally occurring instabilities over thin slender delta wings with sharp leading edges was carried out in a water tunnel using particle image velocimetry (PIV) measurements. Time-averaged location, strength and core radius of conical vortices vary almost linearly with chordwise distance for three delta wings with 75°, 80° and 85° sweep angles over a wide range of angles of attack. Properties of the time-averaged vortex pairs depend only on the similarity parameter, which is a function of the angle of attack and the sweep angle. It is shown that time-averaged vortex pairs develop asymmetry gradually with increasing values of the similarity parameter. Vortex asymmetry can develop in the absence of vortex breakdown on the wing. Instantaneous PIV snapshots were analysed using proper orthogonal decomposition and dynamic mode decomposition, revealing the shear layer and vortex instabilities. The shear layer mode is the most periodic and more dominant for lower values of the similarity parameter. The Strouhal number based on the free stream velocity component in the cross-flow plane is a function of only the similarity parameter. The dominant frequency of the shear layer mode decreases with the increasing similarity parameter. The vortex modes reveal the fluctuations of the vorticity magnitude and helical displacement of the cores, but with little periodicity. There is little correlation between the fluctuations in the cores of the vortices. [ABSTRACT FROM AUTHOR]

Unlabelled: Background The sexual and reproductive health (SRH) knowledge and attitudes of female migrant workers are far from optimum in China. A worksite-based intervention program on SRH-related knowledge, attitude and practice (SRH KAP) modification may be an effective approach to improve the SRH status among migrant workers. This study aimed to identify better intervention approaches via the implementation and evaluation of two intervention packages.Methods: A worksite-based cluster-randomised intervention study was conducted from June to December 2008 in eight factories in Guangzhou, China. There were 1346 female migrant workers who participated in this study. Factories were randomly allocated to the standard package of interventions group (SPIG) or the intensive package of interventions group (IPIG). Questionnaires were administered to evaluate the effect of two interventions.Results: SRH knowledge scores were higher at follow up than at baseline for all participants of the SPIG; the knowledge scores increased from 6.50 (standard deviation (s.d.) 3.673) to 8.69 (s.d. 4.085), and from 5.98 (s.d. 3.581) to 11.14 (s.d. 3.855) for IPIG; SRH attitude scores increased among unmarried women: the attitude scores changed from 4.25 (s.d. 1.577) to 4.46 (s.d. 1.455) for SPIG, and from 3.99 (s.d. 1.620) to 4.64 (s.d. 1.690) for IPIG; most SRH-related practice was also modified (P<0.05). In addition, after intervention, the IPIG had a higher knowledge level than the SPIG; the scores were 11.14 (s.d. 3.855) versus 8.69 (s.d. 4.085), and unmarried women in the IPIG had higher condom use rate than the SPIG (86.4% versus 57.1%).Conclusions: The interventions had positive influences on improvements in SRH knowledge, attitudes and behaviours. Additionally, IPIs were more effective than SPIs, indicating that a comprehensive intervention may achieve better results. [ABSTRACT FROM AUTHOR]

The aerodynamics of thin, flat-plate wings of various planforms (rectangular, elliptical and Zimmerman) have been studied in free-to-roll experiments in a wind tunnel. Non-zero trim angles at low angles of attack, self-induced roll oscillations with increasing angle of attack and even autorotation in some cases were observed. The rectangular wings with round leading-edge had non-zero trim angles at low incidences due to the asymmetric development of the three-dimensional separation bubble at these low Reynolds numbers. With increasing angle of attack, the bubble increases in length and once reattachment is lost, large amplitude roll oscillations develop. The Strouhal number of the roll oscillations is of the order of 10−2, which is in the same range as those expected for small aircraft experiencing atmospheric gusts. Velocity measurements revealed that variations in the strength of the vortices drove the rolling motion. At the mean roll angle, because of the time lag in the strength of the vortices, an asymmetric flow is generated, which results in a net rolling moment in the direction of the rolling motion. [ABSTRACT FROM AUTHOR]

The effects of unsteady trailing-edge blowing on delta wing aerodynamics were investigated experimentally to understand the aerodynamics--propulsion interaction for dynamic thrust vectoring. Two models with sweep angles of Λ 50 and 65 deg, representing nonslender and slender delta wings, respectively, were tested in a water tunnel. Flow visualization and velocity and force measurements were conducted at stall and poststall incidences. For the periodic blowing, it was found that the dynamic response of leading-edge vortex breakdown and wing normal force coefficient exhibit phase lags for both nonslender and slender delta wings. The estimated time constants are larger than those reported in the literature for unsteady wings undergoing pitching or plunging. In the case of transient blowing, the time delay for the decelerating jet is significantly larger than that for the accelerating jet. The variation of the circulation and the reattachment process near the wing surface were studied by means of velocity measurements. The range of the estimated time constants is similar at the stall and poststall incidences for both the slender and nonslender wings. [ABSTRACT FROM AUTHOR]

This article discusses the results of a research study conducted to determine whether self-induced roll oscillation is exhibited in all types of aircraft wings. It is noted that previous research has indicated that this behavior is only present in slender delta wings and low-aspect-ratio rectangular wings due to the close location of their vortices. The study concludes that nonslender wings with high aspect ratios exhibit delta wing rock driven by vortex dynamics and vortex-wing interaction. The researchers suggest that this could be significant to small aircraft with low Reynolds numbers.

Computational simulations have been performed for a 50-deg-sweep delta wing with a sharp leading edge at a 15 deg angle of attack and moderate Reynolds numbers of Re = 2 x 105s, Re = 6.2 x 105, and Re = 2 x 106. A sixth-order compact-difference scheme with an eighth-order low-pass filter is used to solve the Navier-Stokes equations. Turbulence modeling has been accomplished using an implicit large eddy simulation method that exploits the high-order accuracy of the compact-difference scheme and uses the discriminating higher-order filter to regularize the solution. Computations have been performed on a baseline mesh of 11.3 x 106 grid points and a refined mesh of 35 x 106 grid points. An assessment of grid resolution showed that significantly finer-scale features of the flow could be captured on the refined mesh, providing a more accurate representation of the complex, unsteady, separated flow. Comparisons are also made with high-resolution particle image velocimetry images obtained for the two lower Reynolds numbers. The numerical results are examined to provide a description of the mean and instantaneous flow structure over the delta wing, including the separated vortical flow, vortex breakdown, surface flow features, and surface boundary-layer transition near the symmetry plane. The effect of Reynolds number on each of these features is assessed. [ABSTRACT FROM AUTHOR]