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The article presents a method for calculating and designing spherical roller gears with a double-row pinion. The studied gears are analogs of planetary gears with a double-wheel pinion. They make it possible to implement a wide range of gear ratios. The advantages of spherical roller gears include small dimensions, low material consumption, and layout properties. A special feature of the proposed calculation algorithm is the search for optimal geometric gears parameters according to the criteria of maximum efficiency coefficient taking into account maximum load capacity for a given maximum radial dimensions. The main criterion of strength is fatigue endurance. The method includes design and verification calculations. It makes it possible to develop the small-sized speed reducers for low-speed drives for various purposes.

Non-circular gears can be used in modern machines and mechanisms for the implementation of various types of motion and have high strength and compactness compared to linkage mechanisms. This article presents the force analysis of non-circular gear on the example of the planetary mechanism with elliptical gears, providing the rotationally reciprocating motion of the impeller of the stirred tank. Based on the calculation schemes of the links, kinetostatic balance equations for each link of the mechanism are compiled and solved. Reaction forces in kinematic pairs and balancing moment on the input shaft of the mechanism are found. The results can be used in the synthesis and analysis of various machines with the proposed kinematic scheme of the mechanism.

INTRODUCTION In laparoscopic surgery, surgical instruments are inserted from a trocar to the target organ in a blind fashion, which carries a risk of organ injury. To clarify the risks associated with surgical instrument insertion, we measured grip strength and pushing/pressing force during surgical instrument insertion in laparoscopic surgery. METHODS Using forceps with sensors inside a trocar, 10 urologists performed a laparoscopic procedure in pigs, in which they were asked to touch the abdominal wall. The surgeons closed their eyes during the procedure and stopped moving the forceps when they felt them come into contact with the abdominal wall. They were ordered to grip the forceps strongly or softly and to move them rapidly or slowly during the procedure. Grip strength and the pushing/pressing force when the forceps hit the abdominal wall were measured and analyzed. RESULTS The mean pushing/pressing force when the surgeons gripped the forceps strongly and moved them rapidly (strong/rapid), strongly/slowly, softly/rapidly, and softly/slowly were 2.8, 2.0, 1.7, and 1.1 N, respectively. The pushing/pressing force was significantly greater when the surgeons gripped the forceps strongly, regardless of the forceps speed (P

Mobile rope systems designed to carry out loading and unloading and transport and transfer operations in noequipped or hard-to-reach areas and ensuring the prompt deployment of the necessary technological means are a promising type of lifting and transport equipment. The article deals with the layout of the main technological equipment of one of the constructive variants of a mobile rope system on a base multi-axle wheeled chassis of high carrying capacity and performance. A variant of the layout with the central location of the end tower attachment point for supporting the leading rope pulley with a carrying rope on the base chassis frame is considered. Mathematical models have been developed that ensure the kinematic and power analysis of the kinematic scheme of the hydraulic mechanism for installing and fixing the end tower. The analysis of the influence of the main structural dimensions of the indicated mechanism on the dimensions of the mobile rope complex in the transport position, as well as on the force factors arising during the operation of the rope system is carried out. The necessary conditions have been established that must be met when designing a rope system to ensure the regulatory requirements for the movement of a mobile complex on automobile roads of the general using. The conditions for the location and length of the drive hydraulic cylinder of the end tower, which ensure the necessary movement of the tower from the transport position to the working position, have been established and analyzed; the presence of a significant zone of inadmissible location of the hinged assembly for attaching the hydraulic cylinder rod to the metal structure of the end tower has been revealed.

As a kind of typical structure, the hat-shaped structure (HSS) is widely used in carbon fiber reinforced plastics (CFRP) aircraft parts. In this work, a scheme of filling fillers and adding reinforcing plies in R-regions was proposed to strengthen the R-regions of HSS. Moreover, the force analysis of R-region with or without strengthening in R-region under pull-off load was presented. A finite element model was developed to study the failure behavior of R-regions. A series of HSS samples were fabricated by co-curing process. The pull-off tests of HSS were conducted to validate the model, and the failure mechanism of R-regions was further studied by characterizing the macro-micro structure of R-regions in HSS under pull-off load. Results showed that the structural bearing capacity of HSS can be improved by strengthening in R-regions. After strengthening in R-regions, the pull-off load was borne by multiple interfaces, and the interlaminar interface pull-off strength can increase by 38.8 %.

In this study, on the basis of the various contact angles and the hybrid theory, a new mathematic model without the raceway control hypothesis is proposed for the analysis of ball bearing under the combined axial, radial and moment loads. Instead of the orthogonal decomposition method, the triangular geometric theorem and vector diagram method have been used in the force analysis of local ball to improve the computation efficiency of bearing analysis. For validation purpose, the comparative analysis of the ball-raceway contact angles and loads of ball bearing under different operation conditions obtained by the proposed model and the Jones’ model with different raceway control hypotheses has been conducted. The results show that the proposed model has a higher applicability and rationality compared to the Jones’ model, and a proper moment load can be used to improve the load distribution and service performance of ball bearing subjected to the radial load.

Inertial focusing of particles in serpentine microfluidic chips has been studied over the past decade. Here, a study to investigate the particle inertial focusing in 3D-printed serpentine microfluidic chips was conducted by simulation and practice. A test model was designed and printed using four commercial 3D-printers. Commercial inkjet 3D-printers have shown the best printing channel resolution of up to 0.1 mm. The force analysis of particle inertial focusing in 3D-printed microfluidic chips with large cross-sectional channels was discussed. Important parameters such as the channel curvature and flow velocity were studied by simulation. The optimal channel curvature and flow velocity are 5.9 mm and 480 μL min-1 (Re: 29.8 and De: 4.49) in the 3D-printed microfluidic chips with 0.2 mm × 0.4 mm cross-sectional channels. Under these optimal conditions, particles were well focused in the middle of the channel. Furthermore, two kinds of cancer cells were focused in these 3D-printed serpentine microfluidic chips under the optimal conditions. We envision that this improved study would provide helpful insights into simulating particle inertial focusing in 3D-printed microfluidic chips and promoting 3D-printed microfluidic chips to commercial production.

Small and medium-sized businesses (SMEs) contribute significantly to the national economy. In 2018, North Sulawesi had a total of 48.45 thousand SMEs. Indonesian Food and Drug Authority (BPOM) has supports and provides convenience, protection and empowerment for SMEs. In accordance with BPOM's second mission, which is to facilitate the acceleration of the development of the Food and Drug business by partnering with SMEs in order to build a productive and competitive economic structure for the nation's independence. The purpose of this study was to determine the influence of internal and external environment analysis on the performance of Provincial Office of Indonesian Food and Drug Authority in Manado (BBPOM in Manado) as a Technical Implementing Unit (UPT) of BPOM related to registration assistance services to processed food SMEs in North Sulawesi. The company's external and internal environment can affect the company's performance to gain and maintain a competitive advantage. The external environment analysis using PESTEL analysis and Porter’s Five Force analysis while the internal environment analysis using VRIO analysis and RBV analysis. The results showed that internal and external environment analysis could affect on the performance of BBPOM in Manado.

An accurate description of the transition corridor is of great significance for the flight process of the vertical take-off and landing (VTOL) fixed-wing unmanned aerial vehicle (UAV). To study the transition flight process of vertical take-off and landing fixed-wing UAVs, the dynamic model and transition corridor model of this type of UAV are established in the current article. The method for establishing the model is based on a reasonable match of the power and aerodynamic force of this type of UAV. From the perspective of flight dynamics, the ducted lift-increasing system’s deflection angle–speed envelope is studied with the maximum lift coefficient of the wing and the system’s available power. The influence of the overall parameters and energy parameters of the UAV on the deflection angle–speed envelope of the ducted lift-increasing system is analyzed, and a method is proposed to expand the vertical take-off and landing fixed-wing UAV’s transition corridor. Taking the UAV as the object, using the established model, the transition flight corridor of the UAV is obtained, the influence of the control parameters on the transition flight is studied, and the appropriate transition flight control strategy is determined. At the same time, the influence of the overall parameters and energy parameters on the transition corridor is calculated. According to the calculation results, the effect of expanding the flight corridor of the UAV is more obvious when increasing the available power than when increasing the aerodynamic parameters by the same proportion.

The mortality rate of cardiovascular and cerebrovascular diseases is very high, which poses a great threat to human life and health. It has long plagued the middle-aged and elderly people. There are also many young people who suffer from cardiovascular and cerebrovascular diseases. Vascular interventional surgery is an effective means to treat cardiovascular and cerebrovascular diseases, compared with traditional surgery, vascular interventional surgery causes less damage to patients. But interventional surgery will also bring some new problems, for example, the catheter used for surgery needs to pass through long and narrow blood vessels, and lack of real force feedback. In order to avoid or reduce iatrogenic injury, we decided to explore the possible impact of different factors in the surgical process. Firstly, based on real blood vessel size, we designed three simulated blood vessels in vitro. Secondly, through multiple sets of controlled experiments, we successfully explored the impact of robot push speed, blood vessel depth, and blood vessel width on the risk of robot operation. Finally, through the ATI Force/torque sensor to record the data of the tip force of the catheter, through comparative analysis and control variables, we had obtained the influence of different factors on the tip force of the catheter.

Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability, but its force analysis is complex and difficult because the mechanism system contains overconstraints. Considering the limb axial deformation, taking typical 2SS+P and 7-SS passive overconstrained mechanisms, 2SPS+P and 7-SPS active overconstrained mechanisms, and 2SPS+P and 7-SPS passive-input overconstrained mechanisms as examples, a new force analysis method based on the idea of equivalent stiffness is proposed. The equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb deformations. The relationship between the constraint wrench magnitudes and the external force, limb stiffness is established. The equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility equations. Here, the relationship between the magnitudes of the actuated wrenches and the external force, limb stiffness is investigated. Combining with the equivalent stiffness of the passive overconstrained mechanism, an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement, limb stiffness is explored. Finally, adaptability of the equivalent stiffness to overconstrained mechanisms is discussed, and the effect of the limb stiffness on overconstrained mechanisms force distribution is revealed. The research results provide a theoretical reference for the design, research and practical application of overconstrained mechanism.

Rubber tire loaders are key loading equipment for surface and underground mines and can load up to 35 t of material in a pass. Efficient initial penetration into the pile improves the overall efficiency of the loading operation. For efficient design for good initial penetration, we need to predict accurately the resistive forces encountered by these buckets during initial penetration. This paper examines the resistive forces on the bucket as a function of rake angle, height above the digging floor, speed, and tractive effort during initial penetration. A 1/16th scaled representative model of an 18 t (19.8 ton) capacity load haul dump is used for experimentation to understand the effects of rake angle, height above the floor, speed, and tractive effort. The results show that resistive forces are not associated with rake angle or height above the floor but significantly associated with speed, tractive effort, combined effects of speed and tractive effort, and combined effects of speed and rake angle. Future research should focus on conducting similar experiments on different materials and different buckets to better understand the ground engagement for mining and construction equipment. These insights are important to understand the full range of forces during bucket and equipment design.

A cable-driven hyper-redundant manipulator receives great attention due to its slender body and flexible movement. The configuration of the driving cable is the key to manipulator design. At present, cables are arranged at equal angles on the disk, but it lacks theoretical support. The analysis about the influence of cable positions on cable tensions is relatively deficient. In this paper, the force on links is studied. The influence of cable positions on driving force is analyzed. The relationship between cable position, driving force, external force and joint angles are studied. Numerical simulation is carried out to verify the theoretical analysis. The results show the maximum of driving forces is the smallest when cables are arranged at equal angles and decreases as the cable position becomes uniform. The results explain the rationality of the equal configuration of the cables in the cable-driven hyper-redundant manipulator. It’s beneficial to guide the design of cable-driven manipulator.

This paper proposes an electronic trigger assisted coupled and self-adaptive finger, LPCA finger. LPCA finger is provided with two joints, two motors, two sensors and a control module, which realizes coupling during the startup phase of grabbing and self-adaptive in the next stage. According to its self-adaptive characteristics, the device can grasp the target of uncertain size and type. The pressure sensor is used to collect the information of the object contacted by the phalanges, and the second motor can be triggered to cooperate with the assistance of self-adaptive grasping with only a small extrusion pressure to avoid the damage caused by excessive extrusion pressure on the object caused by the proximal phalange in the grasping process. The finger end grasping force is large and the structure is simple. This paper introduces the design of LPCA finger, and gives the force analysis of finger. Force analysis and experiments indicate that LPCA finger possess coupled and self-adaptive function and its end grasping is stable.

In order to Gatling gun's main roller shaft, it shows by using the force analysis. It shows the rotation speed of the main roller shaft is non-constant, it can be determined by the cam curve and the clearance fit between the main roller and the cam curve. The speed of the revolution and position of the main roller shaft was raised and dropped in the core hole. The main roller shaft is sometimes integrated with the bolt movement, but basically, it makes that the main roller only deforms itself, so the main roller shaft is a method for the Gatling cannon. The Gatling cannon needs the main roller shaft more than the Gatling gun. In Gatling cannon, the main roller shaft must be sure to exist. The main roller shaft and bolt body should be two components, not one component. This is the caliber greater than 20mm scheme, and not for the caliber less than 20mm design.

In order to improve the overall strength of the aerial winch drum and reduce the weight of the drum further. The mathematical model of the cable tension acting on the winch drum is built based on the force balance formula, and the relationship between the cable tension and the cable winding layers is analyzed. The multi-layer winding coefficient equation is established according to the actual cable arrangement on drum, MATLAB is used to solve the equation. The simulation results show that the multi-layer winding coefficient increases as the number of winding layers, but the growth rate decreases gradually. When the number of winding layers exceeds a certain value, the multi-layer winding coefficient tends to be stable, and the tension of the inner and outer layers of the cables wound on the drum is larger. This algorithm can be effectively applied to the structural design of aviation winch drum, and provide theoretical basis for practical engineering design.

A newly developed prototype of a soft cable-driven elbow exoskeleton for lifting and lowering of loads was developed. To identify potential harmful forces within the elbow joint, an analysis was conducted with biomechanical simulation. To analyze the effect of the exoskeleton on the human body, biomechanical simulations were conducted on the prototype to assess the joint reaction forces during a lifting task with and without the soft elbow exoskeleton. To reduce these forces, the optimal way to attach the cables for generating the moment around the elbow needs to be identified using biomechanical simulation. First results show that in average the load on the elbow joint is reduced while wearing the exoskeleton compared to lifting 5 kg without any assistance. A large distance between the lower arm and the attachment point in ventral direction is very beneficial, due to the introduction of another lever arm into the system. Especially if the elbow is fully stretched, whereas the pulling force vector would go parallel to the arm. With the implementation of the lever arm, the load on the elbow is lower for any position of the arm.

The diffusion of Internet-based Intangible Network Goods (IINGs) shows new characteristics completely different from that of traditional material products. This paper aims to establish new models t...

Renewable energy sources are growing fast. Nowadays, much effort has been made by inventors to devise new and more efficient configurations of wind turbines. This article describes the mechanical design and resultant force dynamic simulation of an innovative horizontal-axis semi-exposed wind turbine structure. The innovation in wind turbine structure includes the flat shape of its blades and their orientation towards the wind that minimizes the axial component of wind force on the shaft bearings. As a result, wind power is fully utilized to generate a useful rotary force that drives the generator rotor. This enhances the efficiency of the turbine as compared to complex shape blades in traditional horizontal-axis wind turbines. The distinctive feature of the system is also an oscillating shield that automatically protects the generator shaft from overspeeding at extreme wind speeds and, therefore, from generating power above its nominal capacity. The overspeeding may even cause physical damage to the generator. The force analysis of the new wind generator has been conducted for various wind conditions by using ANSYS Fluent. The results are compared to a traditional three-blade horizontal wind turbine to prove the ability of the new semi-exposed wind turbine to collect more driving torque on the shaft. The results of the simulation show the efficiency of the system and the advantage of using this system with the overspeed shield protection.

OBJECTIVE To evaluate recovery of limb function by use of gait force analysis after tibial plateau leveling osteotomy (TPLO) in dogs with unilateral cranial cruciate ligament (CrCL) rupture. ANIMALS 19 dogs with unilateral CrCL rupture treated with TPLO. PROCEDURES Force plate gait analysis was performed before and 1, 2, 4, and 7 months after TPLO. Ground reaction forces (GRFs; which comprised peak vertical force [PVF], vertical impulse [VI], peak braking force, braking impulse, peak propulsion force [PPF], and propulsion impulse), time to switching from braking to propulsion, and vector magnitude at PVF in the forelimbs and hind limbs were evaluated. RESULTS GRFs in the affected hind limb were significantly lower than in the contralateral hind limb before TPLO. These variables, except for PPF, were not significantly different 7 months after TPLO. Time to the switching point in the affected hind limb was significantly less from before to 2 months after TPLO. Vector magnitude at PVF had a similar pattern as PVF and VI during the recovery process. The PVF in the ipsilateral forelimb was significantly higher than in the contralateral forelimb before TPLO. CONCLUSIONS AND CLINICAL RELEVANCE A similar pattern was detected between PVF or VI and craniocaudal force during recovery of dogs that underwent TPLO. Rupture of he CrCl resulted in a decrease in GRFs in the affected hind limb as well as in the switching point and PVF of limbs. However, weight distribution for the craniocaudal force was normalized before PVF or VI. Vector magnitude at PVF might be effectively evaluated by combining vertical force and craniocaudal force.

To achieve the qualitative and quantitative damage expression, coal samples within original cracks were selected to conduct uniaxial compressive loading experiments. During this process, acoustic emission signals were collected by AEwin Test for Express-8.0 and cracks evolution were captured by video camera. The results showed that the larger the initial damage, the lower the uniaxial compressive strength and elastic modulus of coal samples. When coal samples were subjected to uniaxial compression, the primary cracks closed firstly. Then friction phenomenon might generate due to sliding along the cracks surface and the deflection might occur at the center of cracks. Finally, original cracks expanded and new cracks formed and propagated to cause sample fracture, all which leaded to acoustic emission events. AE counts and accumulated counts changed with time, which corresponded well with stress–strain. Therefore, the value of AE counts and the trend of accumulated counts qualitatively explained the damage evolution laws of loaded coal. Further, based on the damage theory of acoustic emission counts, the quantitative damage variable was proposed and calculated. What’s more, the force analysis near the cracks surface at the initial loading process was explained and the cracks dynamic evolution during the whole compressive loading process was discussed. It was helpful to understand the damage evolution mechanism of coal samples.

In this paper an elastic–plastic response has been developed to predict the pull-out behaviour of various hooked end fibres embedded in normal–high strength concretes. An elastic–plastic moment expression has been proposed to represent the partially plastic hinge formed during pull-out. The proposed formula has been incorporated into a frictional pulley force analysis in order to predict the applied loading at each stage of pull-out. This prediction accounts for the variation of geometrical and tensile properties of the fibres as well as concrete strength. The proposed model is validated against experimental pull-out results of various hooked end fibres.

Simultaneous assembly of multiple objects is a key technology to form solid connections among objects to get compact structures in precision assembly and micro-assembly. Dramatically different from traditional assembly of two objects, the interaction among multiple objects is more complicated on analysis and control. During simultaneous assembly of multiple objects, there are multiple mutually effected contact surfaces, and multiple force sensors are needed to perceive the interaction status. In this paper, a coordinated micro-robot manipulation strategy is proposed for simultaneous assembly problem, which is based on microscopic vision and force information. Taking simultaneous assembly of three objects as an instance, the proposed method is well articulated, including calibration of assembly system, force analysis for each contacting surface, and insertion control strategy for assembly process. The proposed method is applicable also to case with more objects. Experiment results demonstrate effectiveness of the proposed method.

The purpose of this study is to present a forward kinematics model of the human lumbar spine and to compare the internal loads and trunk flexion extension with existing literature. The forward kinematics model of lumbar spine with 30 DOF was designed using Solidworks and used Matlab to simulate the results for different postures. The forward kinematics model predicted similar trend for trunk flexion extension, compression force, shear forces and moment as described in literature for in vivo studies. The comparison between the proposed model and in vivo measurement showed a pressure difference of less than 15% on the disc L4-L5 for all activities whereas the compression force and moment differed by ~17% on the disc L5-S1. The modeling methodology presented in this thesis provides a more accurate representation of compression forces and moments of the human lumbar spine since the model makes no assumptions regarding muscle force and does not rely on any other software for kinematics data.

A dental prosthesis, by mimetizing the natural teeth, plays an important role in the maintenance of oral functions (eating, speaking and equilibrium). As the population gets older, the use of implants and implant-supported prosthesis is rising for the replacement of missing teeth. The development of new bio-compatible polymeric materials opens a new window to innovative dental prosthetic for rehabilitation. This project aims to offer patients and healthcare professionals a new product that is significantly faster, cheaper and more beneficial to the success of dental implant treatment. The new solution is based on a universal abutment, compatible with any conventional implant, in a single, simplified retention system, applicable to fixed or removable prostheses, whether total or partial, without the need of screws or cement.

The Rędziński Bridge in Wrocław is the biggest Polish concrete cable-stayed bridge. It is equipped with a large structural health monitoring (SHM) system which has been collecting the measured data since the bridge opening in the year 2011. This paper presents a comparison between the measured data and the finite element method (FEM) calculations, while taking into account 7 years of data collection and analyses. The first part of this paper concerns the SHM application. In the next part, which contains comparisons between forces in cables and temperature changes throughout the structure, the measured data are presented. The third part includes SHM-based calculations and simulations with a complex FEM model to check the measured data and to estimate future measurements. The last part contains a durability assessment calculation for the cable stays.

The effect of maneuver overload on a new type of the multiplanar conformal off-axis four-mirror is studied under the noninertial environment of aerospace. Two kinds of maneuvering flight, horizontal maneuvering and vertical maneuvering, are taken as examples, and the force analysis of the aircraft in the noninertial environment is considered. And the force analysis of the aircraft and the multiplanar conformal off-axis four-mirror is connected by the overload coefficient. Finally, the finite element simulation analysis of the multiplanar conformal off-axis four-mirror is carried out. The results show that the influence of maneuver overload on the multiplanar conformal off-axis four-mirror cannot be ignored. Large overload will result in large deformation of the multiplanar conformal off-axis four-mirror. The deformation is closely related to the structure of the multiplanar conformal off-axis four-mirror. Under the action of lateral force, nonuniform deformation is more likely to occur on the surface of the multiplanar conformal off-axis four-mirror.

Introduction : Existing studies on ecosystem service relationships are mainly qualitative or semi-quantitative assessments, but lack of quantitative exploration of aggregated ecosystem services and their influencing factors. We mapped the distributions of 12 ecosystem services of Zhejiang Province in 2000 and 2015 at the district and county level, analyzed their relationships using Spearman’s correlation analysis, constructed ecosystem service bundle index (ESBI) for each district and county by structural equation model, and then through multiple linear regression, we explored factors associated with ESBI variations. Outcomes : Our results showed that (1) most ecosystem services were spatially clustered. There were synergies between individual ecosystem services in categories of provisioning and regulating services, respectively; (2) our proposed ESBI index system consists of overall index and sub-indices of provisioning, regulating, and cultural services. The higher the ESBI value, the more important the corresponding place for multiple aggregated ecosystem service provision. Compared to 2000, ESBI in 2015 distributed more unevenly, and the average dropped by 3.10%; and (3) the increase of ESBI was associated with its initial value, and four socioeconomic and natural factors; the decrease of ESBI was influenced by the initial value and six key socioeconomic factors. Discussion and Conclusion : Our proposed ESBI system has several advantages (e.g., scale free, flexible weighting, quantitative and continuous indices for further analyses, and alternative non-monetary solution) in understanding and managing relationships among multiple ecosystem services.

Introduction: Large-scale disordered coastal aquaculture development causes severe environmental problems. However, quantitative assessments of spatiotemporal dynamics and driving factors for coastal aquaculture are essential and urgent for coastal aquaculture sustainability. Outcomes: Using remote sensing products and geographic information science, we investigated the long-term landscape changes due to coastal aquaculture, and explored its underlying driving factors in the Ningde coastal region, Southeastern China. Results show that coastal aquaculture area increased from 90.65 km 2 in 2003 to 96.08 km 2 in 2016, and its structure underwent tremendous changes. The area of artificial shrimp ponds increased by 496.15% and the area of farmland ponds decreased by 25.81% between 2003 and 2016. In addition, we revealed that from 2003 to 2016, the change trends of the coastal aquaculture area and the entire Ningde coastal region were consistent, and became more fragmented and dispersive. Furthermore, regression results indicate that the growth and attenuation of coastal aquaculture areas were significantly affected by the initial coastal aquaculture area in 2003. Discussion and Conclusion: To sustainably manage the coastal ecosystems, we provide several recommendations (e.g., a coupled human and natural systems approach to understanding human-nature interactions, integrated assessment, and systematical spatial planning and monitoring) for future research and management.

Subway electric passenger cars have a large capacity, high efficiency, high-frequency door set control switch and other characteristics, so it requires the door safety, reliability, low failure rate. This paper mainly aims at the force analysis calculation and structural optimization of the fault of the screw break of the synchronous rod bracket, so as to avoid the same kind of fracture situation.

Launching technology with rocket booster is widely used in the launching process of UAV. In this paper, the process of short rail launch with rocket booster was divided into three phases. Through the force analysis of all the phases, a complete mechanical model of the whole launching process was established. Then the short rail launch of an UAV was taken as an example, and the influence of rocket installation angle, UAV emission angle and the effective length of short rail on launching process was analyzed, and the appropriate launching parameters were selected. After that, the attitude changes of UAV when the rocket thrust doesn’t pass through the center of gravity were obtained and compared with that of zero-length launching process. The results show that due to the constraint of short rail, the flight attitude variation range of UAV during the launching process is smaller than that of zero-length launch, which is more conducive to the launching safety.

The western region of China is rich in mineral resources. The vigorous development of mineral resources has exacerbated the environmental and safety problems in the region. One of the important links to solve this problem is to control the development laws and distribution characteristics of the overburdened cracks in the mining of this area. In this paper, the Xiashijie coal mine 3-2 coal seam and 4-2 coal seam are examples of repeated mining, and are examined as the background, through theoretical analysis to optimize the size of the coal pillars in the lower section, using the 3DEC numerical simulation experiment method and the rise of the cracks in the short-distance coal seam. Repeated mining monitoring and analysis of the development law are used to ascertain distribution characteristics of overburdened cracks caused by the repeated mining process of the working face. The results show that: (1) By establishing a mechanical model of the overlying strata structure under short-distance coal seam group mining, and carrying out the force analysis of the double section coal pillar under repeated mining, the reasonable size of a lower section coal pillar was determined to be 70 m. (2) As the development height of a fracture progresses with the working face, its expansion rate undergoes four obvious changes: fluctuations within a certain range, the expansion rate reaches the peak after the rock formation is concentrated and broken, the cyclical change gradually decreases, and the expansion rate is zero after complete mining. (3) The fracture zone height of 222 and 224 face under repeated mining in the 4-2 coal seam was 19.56&ndash, 22.31 times and 22.38&ndash, 24.54 times larger, respectively, and the post-mining fracture extension of the face with larger width and deeper burial under repeated mining was higher than that of the adjacent face. This study provides scientific guidance for the rational division of coal pillars and the solution of the problem of water conservation mining under repeated mining in the adjacent face of a short-distance coal seam.

There are ample literature addressing the dynamic analysis for gears. In this paper, some important literature on dynamics of both healthy gears and gears with defects have been reviewed. Dynamic analysis of gears is significant from the condition monitoring point of view. Single degree of freedom dynamic model for spur gears has been detailed first. Dynamic study for worm gear with force analysis has been reported. Also, the effect of defects like crack and spall on dynamic behavior of gears studied by researchers has been included in this review. The study of defect model can be utilized in improving the efficiency of the system and preventing the failures in industries as well.

BackgroundDenis and Ferguson et al.’s three-column spinal theory has been widely accepted and applied. However, this three-column theory was proposed based solely on observation and experience without thorough documented data and analysis. The aim of this study was to analyze and improve Denis and Ferguson et al.’s three-column spinal theory to propose a novel three-column concept in epidemiology, morphology and biomechanics.MethodsA retrospective analysis of the computed tomography imaging data of patients with a diagnosis of T11-L5 vertebral fractures was conducted between February 2010 and December 2018. Three-dimensional (3D) distribution maps of fracture lines of all subjects were obtained based on 3D mapping techniques. In addition, a 25-year-old health male volunteer was recruited for the vertebral finite element force analysis.ResultsThe present study enrolled 459 patients (age: 48 ± 11.42 years), containing a total of 521 fractured vertebrae. The fracture lines peaked in the upper and the outer third sections of the vertebra, starting from the anterior part of the vertebral pedicles in 3-D maps. Regarding flexion and extension of the spine, the last third of the vertebral body in front of the spinal canal was one main stress center in the finite element analysis. The stress on the vertebral body was greater in front of the pedicles in the lateral bending.ConclusionThe study reveals that the posterior one-third of the vertebral body in front of the spinal canal and the posterior one-third of the vertebral body in front of the pedicle are very different in terms of fracture characteristics and risks to spinal canal (3D maps and stress distributing graphs), therefore, they should be classified as different columns. We provide strong evidence that Su’s three-column theory complies with the characteristics of vertebral physiological structure, vertebral fracture, and vertebral biomechanics.Graphical abstract

Further the large deformation problem of compliant mechanisms is investigated in this chapter. As has been discussed in Sect. 4.4.4, when a compliant mechanism is under a large external load, the corresponding stiffness matrix is no longer symmetric and invariant. However, its force equilibrium still holds the same and it is used here to explore the compliant mechanism’s large deformation properties. It is straight forward to conduct inverse force analysis of compliant serial mechanisms and forward force analysis of compliant parallel mechanisms. However, additional consideration is needed for compliant mechanisms that have mixed configurations. In accordance with this, a repelling-screw based force analysis approach is developed in this chapter, making it possible to conduct a forward force analysis of compliant mechanisms that have hybrid combinations of flexible elements. This proposed force-modelling approach is further applied to analyze the large deformation behaviours of origami-inspired compliant mechanisms. An origami-inspired compliant mechanism is a foldable structure that consists of both panels and creases, which can be treated as an equivalent mechanism by taking panels as links and creases as revolute joints. Thus an origami mechanism can be treated as a parallel mechanism with revolute joints. Section 8.2 presents a complete experimental test of single creases of origami folds, which reveals an origami crease can be treated as a one-DOF flexible element with embedded torsional stiffness. This paves the way for the further force analysis of origami compliant structures using the proposed repelling-screw based approach. The theoretical background of this approach is provided in Sect. 8.3 in the framework of screw theory, and it is utilized to conduct force analysis of several typical origami compliant platforms in the following Sects. 8.4 and 8.5 respectively.

The whole structure of large turbogenerator is very complex. This paper mainly analyzes the electromagnetic force on stator end winding of turbogenerator. Based on the involute model of stator end winding wire rod, the concrete mathematical analytical formula is established. The electromagnetic force of wire rod of different rods, at different times and the electromagnetic force at different positions of the same wire rod are analyzed. It is of great significance to the optimization design and operation maintenance of stator end windings of large turbogenerator.

Controllable lunar landers with magnetorheological fluid (MRF) damper have become a hot topic of research. However, limited research studies have been performed on the damping force analysi...

The paper describes the measurement of ovality of large induction machine rotor and the calculation of the air gap size along the rotor circumference. Also the withdrawal forces are calculated and the causes for its decline are discussed. The model is assembled and the influence of rotor ovality on the machine stator is described.

In view of the frequent failure of the ball-eye (BE) in the transmission line, the force analysis of BE in extreme weather is carried out, and a set of bending fatigue test equipment was designed. It is the first time to carry out the fatigue test of BE treated by normalising, annealing and quenching and tempering process under bending loads of 2330, 3495 and 4560 N. Meanwhile, the bending fatigue life curve is plotted. From the macro and micro point of view, the characteristics and the content of the elements of the fracture, and the influence of the internal structure on the mechanical properties of three samples of different heat treatment processes are analysed. Conclusion indicates that the mechanical properties of the BE treated by normalising process are best, whose microstructure is fine and uniform ‘ferrite + pearlite’. Comparing the life of BE withstood tension load, it is revealed that bending load is the main reason to accelerate the failure of BE.

China's chemical industry has greatly altered the processes that contribute to reactive nitrogen (Nr) creation and Nr emission. However, the fluxes, fates and environmental consequences of Nr produced by the chemical industry remain poorly understood and unquantified. We report here that Nr creation and Nr emission by the chemical industry increased 47- and 37-fold from 1963 to 2015, respectively. Nr fixation in the chemical industry mainly results from the production of N fertilizer, but Nr fixation by fossil fuel combustion and chemical N products (except N fertilizer) has rapidly increased over the past 15 years. Meanwhile, the manufacture of raw chemical materials and chemical products are the main contributors to waste Nr production. Driving force analysis of Nr creation and Nr emission shows that population growth has the largest positive effect, while urbanization also has varying degrees of impact. Additionally, we propose some policy suggestions to reduce the environmental impact of Nr emissions from the chemical industry based on a brief future perspective of Nr creation and Nr emission. These findings will provide policy makers with an integrated view of Nr metabolism and environmental damage to address the significant challenges associated with reducing emissions in the chemical industry.

Applying prestressing techniques increases the load carrying capacity of girders, leading to substantial saving in construction material. In addition, prestressing a steel girder reduces its deflection under external loads, and thus, enhances its flexural behavior. The aim of this study is to use a finite-element formulation to verify the effectiveness of the prestressing technique with respect to the flexural behavior of a steel plate girder. The strength of two steel box girders is tested, one with prestressing (prestressed girder) and one without (control girder). Based on experimental results, a theoretical model is proposed for predicting the flexural resistance of a steel box girder with external tendons. To improve the calculation accuracy, finite-element formulation is applied to prestressing and external loading stages of the girder and external tendons, which are regarded as composite structures, and the interactions between them are fully considered. The friction between tendons and deviators is considerably small. Therefore, the friction resistance between the tendons can be neglected during the force analysis. The strain in the prestressed girder is distributed linearly along its height, indicating that the calculation performed using the plane section assumption is consistent with the actual situation for the same external load. The experimental and theoretically calculated values of strain in the bottom plate of a steel girder and tension force increment for deflections at mid-span and quarter span are in good agreement. This indicates that the finite-element formulation proposed in this study is correct and efficient.

Thousands of spherical fuel elements are transported pneumatically in pipelines in a pebble bed reactor every day. The motion of the fuel element has a strong influence on the efficiency and reliability of the reactor. The motion is determined by the force condition of the fuel element which is determined by the characteristics of the flow field in turn. Thus, it is of great significance to analyze the characteristics of the flow field and the force conditions of the fuel element. In this paper, we carry out simulations of the flow field with a structured mesh based on CFD (computational fluid dynamics). We analyze the effect of the motion and position of the fuel element on the flow field. Then we accomplish the force analysis of the fuel element in the flow, and acquire the fitting formulae of the force and torque on the fuel element. The experiment was performed on the experimental platform. The experimental results are in agreement with the theoretical analysis and verify its accuracy. This research may provide an important rationale for the dynamic and kinematic analysis of the fuel element pneumatic transportation as well as the basis for the stable operation of the reactor.

Based on a data envelopment analysis framework, this study develops an indicator termed as carbon-weighted economic development (CWED) covering the dimensions of energy, environment, economy and resources to measure the economic development performance in a carbon-emission conscious economy. As an empirical application, the proposed approach is applied to a case study of 30 provinces in China. In addition, to identify the driving forces underlying low-carbon economic development in China, we analyze the endogenous interactions and dynamic behaviors between CWED, Foreign Direct Investment, foreign trade, industrial structure, local fiscal expenditure and energy consumption structure using a panel vector auto-regression model. The main findings show that, (1) adjusting industrial structure by vigorously developing the service industry and reducing the coal energy share in the primary energy consumption structure are the two most effective approaches to improve CWED in both the short-run and long-run; in return, CWED has positive feedback effects on both approaches in the long-run; (2) increase of the fiscal expenditure has a short-term positive effect on CWED; (3) FDI has an indirect negative effect on CWED in the long-run and foreign trade has an indirect positive effect on CWED in the short-term.

The slippage of cable clamps during the long-term operation of suspension bridges is a common and detrimental phenomenon. From an experimental point of view, the cable clamp slippage of a suspension bridge was investigated to reveal the effect of this sliding on the force acting on the full bridge. The forces acting on the bridge before and after the slippage were analyzed using a finite element model. The calculation results showed that the cable clamp slippage directly affects the cable forces of the hangers. The hanger cable force decreased by 19.2% when the slippage reached 10.2 cm, while the maximum increase in the cable force of adjacent hangers was 147.7 kN, an increase of 7.25%. The variation of forces in the hanger cable disrupted the force balance of the main girder, thereby producing a torque effect at the corresponding position in the girder, i.e., increased torque. Meanwhile, the slippage affected the axial tension in the main cable and the main girder. The impact of the tower internal force was less than 1%. Hence, the study concluded that the effect of cable clamp slippage is better understood, ensuring the safety of the suspension bridge.

Prefabricated small box girder bridges have been widely used in urban viaducts and highway bridges at home and abroad. Concrete deck paving and guardrails are well bonded to the main girder, which contributes to the rigidity of the main girder structure. Ignoring the influence of the auxiliary structure of the bridge deck will cause a certain deviation between the structure and the actual state. This paper takes the prefabricated box girder bridge as an example, using the finite element method to analyze the variation of the lateral distribution coefficient of the bridge deck and guardrail and the degree of influence on the main girder force. The calculation results show that the bridge deck pavement has little effect on the lateral distribution coefficient of the main girder, the increase in the rigidity of the main girder by the guardrail cannot be ignored, and the difference in the bearing capacity and stress of the side main girder is significant.

This paper presents a multilink-articulated robot with omni and hemispherical wheels (AIRo-2.1) for inspecting and exploring pipelines. To quickly adapt to winding pipes, holonomic rolling movement...

This paper compares three common installation ways of swing arm and carries out simulation analysis by using Adams software. The research results show that when using intercrossed enwinding wirerope, the swing arm will bear alternating load and the load variation range is huge, load G’ will change obviously and bring great impact on system control precision. When using along enwinding wirerope, the swing arm’s load is slightly bigger than wirerope tension and the load variation range is very small, load G’ will be static and it’s easy to get high control precision. By reducing the length of lower swing arm, increasing the length of upper swing arm and the offset distance, its working condition can be improved when using intercrossed enwinding wirerope.