Direct Pulling Research Articles

A Cable-Driven Parallel Hip Exoskeleton for High-Performance Walking Assistance

Misalignment between human and exoskeleton joints is a common issue in exoskeletons of rigid structure, as it can lead to discomfort or even injuries. Cable-driven exoskeletons, by using human skeletal joints, remove misalignment as a potential issue. However, large parasitic forces due to cable pulling endure as a shortcoming of cable-driven exoskeletons. To address the problem, this paper proposes a novel cable-driven hip exoskeleton of parallel structures for assisted walking with eliminated parasitic force. The parasitic force potentially caused by either the misalignment or direct pulling can be removed mechanically. The new exoskeleton, conceptually different compared to existing anthropomorphic exoskeletons or soft exoskeletons, can conjugate flexibility and kinematic redundancy in flexion/extension and ab/adduction for self-alignment with anatomical joints. The unique design enables internal/external rotation for versatile walking gaits. In the work, the misalignment between the mechanical and biological hip joints is quantified both theoretically and experimentally. Moreover, an adaptive robust controller (ARC) is designed to provide desired force during assisted walking. Experimental results demonstrate the performance of the proposed cable-driven exoskeleton system and improved wearing comfort with parasitic forces eliminated.

Generation of Inverted Locomotion Gait for Multi-Legged Robots Using a Spherical Magnetic Joint and Adjustable Sleeve

In this paper, we propose the design and implementation of spherical magnetic joint (SMJ)-based gait generation for the inverted locomotion of multi-legged robots. A spherical permanent magnet was selected to generate a consistent attractive force, enabling the robot to perform inverted locomotion under steel structures. Additionally, the robot’s foot tip was designed as a balljoint mechanism, providing flexibility in foot placement at any angle between the tip and surface. We also introduced an adjustable sleeve mechanism to detach the foot tip during locomotion by creating a fulcrum during the tilt and pull steps. This mechanism effectively reduced the reaction force based on the sleeve diameter. The experimental results showed a 46% decrease in the present load when using the adjustable sleeve mechanism compared to direct pulling. For inverted locomotion, a quadruped robot and a hexapod robot, which represent the predominant type of multi-legged robots, were constructed. We integrated the SMJ and adjustable sleeve into both robots, enabling them to perform inverted locomotion with various gaits such as crawling, trotting, square, and tripod gaits. Our analysis examined the characteristics of each gait in terms of velocity and stability, thereby confirming the versatility of the proposed SMJ, which can be applied to different types of legged robots.

Design for Disassembly of Concrete Slabs with Mortar Joints

A sustainable future is required for precast concrete structures, and the reuse of concrete elements will be an essential part of the solution. Design for disassembly is currently conducted with costly and time-consuming mechanical joints. Now, mortar joints with much weaker mortar types are proposed for new buildings, enabling easier disassembly by new methods: removal by direct pulling and removal by use of a system of flat jacks. Different weak mortar types were tested in the lab to achieve the properties required to check the transfer of wind loads and the level of resistance to separation during disassembly. Using a modelled case study building, the results showed that weak lime cement-based mortars had the required properties to substitute regular cement-based mortar in joints between slabs and a stabilising wall during a critical wind load. Regarding disassembly, pulling concrete slabs out with a mobile crane would be possible if hydro demolition systems could be implemented to remove parts of the mortar joint beforehand. Using a system of flat jacks to push the slab apart showed that the method’s weakness was the punching failure of the thin wall to the hollow cores. Solutions were proposed to overcome the challenge.

Adhesion of structural steel to concrete with recycled crushed sanitary ceramics aggregate

Today, the use of recyclable materials has been the focus of researchers around the world. The use of re-cycled concrete aggregates, although beneficial for environmental reasons, brings many problems. One of the basic factors is the presence of old mortar and impurities in these aggregates. Therefore, it is necessary to conduct comprehensive studies in this field. Hence, the paper presents the results of testing the adhesion of B500SP structural steel to concrete subjected to thermal loads in the range of 300–700°C. The concretes were designed exclusively based on waste aggregate made of precious waste ceramics and two types of cement: CEM I 42.5 R portland cement and Górkal 70 alumina cement. The method of direct pulling of a steel rod from the concrete cover (pull-out test) was used in the tests. The test results confirmed that the adhesion of the selected steel grade to concrete based on recycled aggregate does not differ from the results obtained for concrete with natural aggregate.

Two energy barriers and a transient intermediate state determine the unfolding and folding dynamics of cold shock protein

Cold shock protein (Csp) is a typical two-state folding model protein which has been widely studied by biochemistry and single molecule techniques. Recently two-state property of Csp was confirmed by atomic force microscopy (AFM) through direct pulling measurement, while several long-lifetime intermediate states were found by force-clamp AFM. We systematically studied force-dependent folding and unfolding dynamics of Csp using magnetic tweezers with intrinsic constant force capability. Here we report that Csp mostly folds and unfolds with a single step over force range from 5 pN to 50 pN, and the unfolding rates show different force sensitivities at forces below and above ~8 pN, which determines a free energy landscape with two barriers and a transient intermediate state between them along one transition pathway. Our results provide a new insight on protein folding mechanism of two-state proteins.

Anisotropy in mechanical unfolding of protein upon partner-assisted pulling and handle-assisted pulling

Proteins as force-sensors respond to mechanical cues and regulate signaling in physiology. Proteins commonly connect the source and response points of mechanical cues in two conformations, independent proteins in end-to-end geometry and protein complexes in handshake geometry. The force-responsive property of independent proteins in end-to-end geometry is studied extensively using single-molecule force spectroscopy (SMFS). The physiological significance of the complex conformations in force-sensing is often disregarded as mere surge protectors. However, with the potential of force-steering, protein complexes possess a distinct mechano-responsive property over individual force-sensors. To decipher, we choose a force-sensing protein, cadherin-23, from tip-link complex and perform SMFS using end-to-end geometry and handshake complex geometry. We measure higher force-resilience of cadherin-23 with preferential shorter extensions in handshake mode of pulling over the direct mode. The handshake geometry drives the force-response of cadherin-23 through different potential-energy landscapes than direct pulling. Analysis of the dynamic network structure of cadherin-23 under tension indicates narrow force-distributions among residues in cadherin-23 in direct pulling, resulting in low force-dissipation paths and low resilience to force. Overall, the distinct and superior mechanical responses of cadherin-23 in handshake geometry than single protein geometry highlight a probable evolutionary drive of protein-protein complexes as force-conveyors over independent ones.

An innovative interface reinforcement method for steel bridge deck pavement pothole repair

Due to the special supporting condition, severe environment and high traffic load, pothole distress becomes very common in steel bridge deck pavement (SBDP). In this paper, an interface reinforcement method considering the mechanical response characteristic of SBDP pothole interface was designed and presented, which involves of adhesive layer, non-woven fabrics (NWF) layer, and ultra-thin asphalt overlay (UTAO). To assess the effectiveness and present a theoretical basis for this proposed technique, the mechanical response changes of reinforced SBDP pothole interface were clarified through finite element models (FEMs) in consideration of NWF orthotropic elastoplastic properties in this article. Furthermore, bonding performance between NWF and SBDP, direct cracking resistance performance and anti-fatigue performance of the interface reinforcement were evaluated through direct pulling test, three-point bending test and fatigue beam test, respectively. Results show that this innovative method using NWF layer and UTAO can mitigate horizontal tensile stress state in SBDP pothole interface obviously. The direct and fatigue cracking resistance of the repair interface also improve greatly. It is a suitable method to guide SBDP pothole repair, and the strength and durability of the repaired interface are comparable to that of a newly constructed SBDP.

The Mechanism of Flex-Activation in Mechanophores Revealed By Quantum Chemistry.

Flex‐activated mechanophores can be used for small‐molecule release in polymers under tension by rupture of covalent bonds that are orthogonal to the polymer main chain. Using static and dynamic quantum chemical methods, we here juxtapose three different mechanical deformation modes in flex‐activated mechanophores (end‐to‐end stretching, direct pulling of the scissile bonds, bond angle bendings) with the aim of proposing ways to optimize the efficiency of flex‐activation in experiments. It is found that end‐to‐end stretching, which is a traditional approach to activate mechanophores in polymers, does not trigger flex‐activation, whereas direct pulling of the scissile bonds or displacement of adjacent bond angles are efficient methods to achieve this goal. Based on the structural, energetic and electronic effects responsible for these observations, we propose ways of weakening the scissile bonds experimentally to increase the efficiency of flex‐activation.

Effect of Harvesting Methods on Storage Behaviour of Mandarin (<i>Citrus Reticulata</i> Blanco) Under Cellar Condition

Mandarin (Citrus reticulata Blanco) is a premier fruit crop expanding rapidly in the hilly areas of Nepal. Most of the mandarin growers in Nepal are using conventional harvesting method which is responsible for deteriorating the fruit quality and shortening the postharvest shelf life. Thus, this experiment was conducted to evaluate the effect of different harvesting methods on quality and shelf-life of mandarin during storage under the Cellar condition (11±2°C and 85-90% RH). For this, mandarin fruits harvested by different methods i.e. hitting by sticks, direct pulling, twisting and pulling, and clipping were stored for 90 days and fortnight interval reading of different quality parameters were carried out. The experimental results revealed that fruits harvested by clipper with small pedicel intact recorded the minimum PLW (3.15%), decay loss (8.33%), and TSS (10.57° Brix) and retained the higher fruit firmness (3.30 kg/cm2), maximum juice recovery percentage (49.69), TA (0.85%) and vitamin C (25.50 mg/100 ml) during the storage under Cellar condition. The study concluded that fruits harvesting with clipper can be stored safely up to three months under the Cellar condition.

Measurement of Adhesion of In Situ Electrospun Nanofibers on Different Substrates by a Direct Pulling Method

In some cases, we hope to remove the electrospun nanofibrous mesh from the collector easily. But in some cases such as wound dressing, we observe that the in situ electrospun nanofibers can stick to the collector (e.g., skin). Therefore, the adhesion between the in situ electrospun web and the substrate becomes important in the performance and practical application of the electrospun material. In this paper, we reported a direct pulling method to measure the adhesion and understand the adhesion mechanism. In this method, we used gravity to pull the fiber directly from the substrate and then measured the gravity to calculate the adhesion. This new test method is more convenient and practical than the previously reported methods. In addition, the adhesion of the in situ electrospun web on different substrates (e.g., aluminium foil, wood pulp paper, and silicon paper) was also studied by this method. The adhesion was influenced by spinning voltage, electrical conductivity, and surface roughness of the substrates.

Positioning of China's Real Estate Industry Based on Input-Output Analysis

Executive Summary. By way of input-output analysis, we express China's real estate industry position in terms of its industry linkage effect, industry spread effect, and industry clusters division. Using China's 42 sector input-output table, related economic indexes are quantitatively examined. From an industry linkage effect standpoint, the direct driving force from the real estate industry primarily acts on the tertiary industry and is the total driving force behind the secondary industry. Direct pulling power uniformly applies to both the secondary and tertiary industries, and total pulling power mainly acts on the secondary industry. As far as the industry spread effect is concerned, China's real estate industry shows a slight pulling effect and a promotional effect on the national economy. Based on an industry clusters divisional analysis, the real estate industry in China is a final demand and basic industry.

Cavity morphogenesis: imaging mitotic forces in action

Cavity morphogenesis: imaging mitotic forces in action

Thickness Indirect Measurement Method for Direct Pulling Pilot Cold Rolling Mill

Pilot cold rolling mill is the important tool for the cold rolling process researching and new steel grade development. According to the design of the new type direct pulling pilot cold rolling mill, based on the mass flow constant principle, strip exit thickness indirect measurement method is studied. During rolling, strip entry and exit speed can be calculated accurately according to the measured value of two sides’ clamps movement. Data filtering treatment is adopted and program flow chart is designed. Based on the material entry thickness measured manually, exit thickness of all passes can be measured indirectly. This thickness indirect measurement method has been applied successfully on the new type pilot cold rolling mill, and the measurement results show that this method has a good accuracy.

A 4.75-GHz Fractional Frequency Divider-by-1.25 With TDC-Based All-Digital Spur Calibration in 45-nm CMOS

This paper presents a fractional frequency divider-by-1.25 and associated all-digital calibration circuitry. The divider can be used in a wireless transceiver to prevent direct or harmonic pulling of the VCO by the power amplifier. Timing errors between the quadrature phases used in the phase-rotating divider introduce fractional spurs at the output. In this design, the timing errors are measured with a stochastic time-to-digital converter with 20 fs resolution, and corrected to suppress output spurs. The fractional divider has been implemented in a 45 nm CMOS LP process and its core dissipates an estimated 17 mA current from a 1.1 V supply. After calibration, fractional spurs are on average below -59 dBc and -50 dBc (¿ ~ 2 dB over 10 samples) with a 2.5 and 3.8 GHz output frequency respectively. Calibration performance has been confirmed for temperatures from -20°C up to 85°C. The low spur level facilitates radio co-existence with no need for additional filtering. This makes this divider a good candidate for WiFi and WiMAX radios up to 3.8 GHz.

The Safest Method of Sternal Wire Extraction Post-Midsternotomy Closure

An incident of fatal pericardial bleeding immediately after the extraction of a sternal wire prompted a search for the most appropriate method for removing sternotomy wire sutures. A model sternum was devised to explore this problem, and several commonly used techniques for wire extraction were evaluated. A wooden sternal model was constructed to simulate the dimensional properties of a sternum overlying the mediastinal cavity, and to imitate its tensile characteristics. A Monofil CrNi-316L (Johnson & Johnson, Brunswick, NJ, USA), No. 7 CCS, 9 metric, 4x45-cm wire was passed vertically through drilled holes. The suture was then crossed and pulled, thus joining the two boards and approximating the wire to their deep surface. A latex balloon filled with dye was placed inside under the boards. Wire holders were used to extract the wires, using a linear pulling technique and a coiling around the wire-holder tip technique. Sixty repetitions were performed for each method. In 60 trials of direct linear wire pulling, balloon rupture occurred in 33 (55%), whereas tearing was noted only 15 times out of 60 attempts (25%) when the tense coiling method was used. Sternotomy wire sutures should be extracted using a controlled technique that ensures safety to vital tissues in close proximity to the sternal bone. The tense coiling procedure offers superior safety when compared to the direct pulling process, demonstrated by a lower incidence of balloon rupture because of the lesser degree of wire flexure. This technique has become the method of choice in our medical center.

A case of high-pitched diplophonia that resolved after a direct pull of the lateral cricoarytenoid muscle

Various approaches have been employed for the surgical treatment of unilateral vocal cord paralysis. Recently, we performed a direct pull of the lateral cricoarytenoid muscle in a case of high-pitched diplophonia with little difference between the right and left vocal cord levels and obtained favorable results. The patient was a 66-year-old male who consulted our hospital with chief complaints of husky voice and abnormal sensation in the pharyngolaryngeal region. Cerebellum/brainstem inflammation was diagnosed in February 2002 and appropriate treatment was instituted. Despite an improvement in the patient's systemic condition, right vocal cord paralysis remained. Although there were no abnormalities in the vocal range for ordinary speech, diplophonia was noted at high pitches, and synchronization could not be observed using stroboscopy. Therefore, the patient was operated on in October 2002. The high-pitched diplophonia disappeared and stroboscopy revealed favorable mucosal waves at high pitches. Thus, direct pulling of the lateral cricoarytenoid muscle appears to be a useful procedure, even in a case of mild unilateral vocal cord paralysis.

Improved technique of heterotopic cervical heart transplantation in mice.

The method for mouse vascularized heart transplantation have been described using suture and cuff techniques. Technical problems have limited its widespread use. Here, we describe our method of modified cervical heterotopic transplantation with the cuff technique. By using a smaller Teflon cuff (external diameter 0.6 mm, internal diameter 0.4 mm) and superfine-tip forceps, it became possible to directly pull the edge of the carotid artery and evert the proximal end of the artery over the cuff. Similarly, the external jugular vein could be easily everted over a 22-gauge cuff with this direct pulling method. By these modifications, the operation time was reduced. It usually takes 20 min for the donor harvest, 15 min for preparation of the cervical vessels, and 15 min for anastomosis. All procedures from the donor harvest through skin closure of the recipient mice can be completed within 1 hr, and ischemic time is within 25-40 min. This method can be used to investigate cyclophosphamide-induced tolerance and mechanisms of reperfusion injury.

High pressure Czochralski growth of Fe 1−xS (0< x≤0.1) single crystals

The high-pressure Czochralski growth of Fe 1− x S crystals (0< x≤0.1) is described. As x approaches zero (troilite) the low equilibrium vapour pressure of sulphur permits direct pulling under an argon pressure of 20 atm. The occurence of defects such as cells and Fe/FeS eutectic structures are related to the incongruent melting of such crystals; the occurence of cracking is related to the anisotropic thermal expansion which has been measured by X-ray diffraction at temperatures in the range 20–500°C. Congruently melting crystals ( x≅0.1) have been grown using the high-pressure B 2O 3 liquid encapsulation technique to prevent sulphur vapour loss (equilibrium vapour pressure of sulphur ca. 1 atm). Although B 2O 3 does not wet the growing crystal, growth at the congruent melting composition offers advantages with respect to the occurence of defects such as cellular structures, oxide inclusions and cracking.