Vertical Board Research Articles

Gluing parameters optimization and failure mechanism of cross-laminated timber prepared with Chinese fir

Cross-laminated timber (CLT) has become a popular engineered wood product, mainly prepared from imported wood in China. More extensive research is needed to improve the local production of cross-laminated timber with fast-growing coniferous wood species. Chinese fir (Cunninghamia lanceolata) and one component polyurethane (1C-PUR) adhesive were selected to prepare CLT under different process parameters. International standard methods, scanning electron microscopy (SEM), optical microscopy (LM), confocal laser scanning microscopy (CLSM), and nanoindentation (NI) were applied. The bonding performance and failure mechanism of Chinese fir CLT were investigated and clarified. The results showed that the optimal gluing parameters for preparing CLT from Chinese fir wood were 160 g/m2 of glue, 0.9 MPa of pressure, and 180 minutes of pressing time. Failure of CLT made from Chinese fir lumber was mainly due to the shear failure of the vertical layer board. Cracks often appeared in the earlywood cells near the boundary between earlywood and latewood. The impact of adhesive penetration on the mechanical properties of the wood cell wall showed that adhesive penetration increased the elastic modulus of the cell wall at earlywood and latewood cells.

Effects of galvanic vestibular stimulation on postural righting reactions in hemiplegia

Patients with post-stroke hemiplegia often exhibit reduced ability to maintain sitting balance, a crucial factor for predicting prognosis. Galvanic vestibular stimulation (GVS) influences postural control by stimulating vestibular organ. Although several studies have focused on GVS in static postures, no studies have demonstrated the influence of GVS on righting reactions. Therefore, we aimed to investigate the effects of GVS on postural righting reactions in seated patients with stroke-induced hemiplegia. Using a vertical board (VB), righting reactions were induced by tilting the VB at 10° after patients sat for 1 min. Patients adjusted their bodies until feeling vertical upon prompt. Twenty-two left hemiplegic patients with cerebrovascular disease participated, divided into two groups undergoing right cathode GVS (RC-GVS) followed by left cathode GVS or vice versa, preceded by sham stimulation. Centre of pressure and the joint angle were measured. During the postural righting reactions towards the paralysed side, RC-GVS enhanced the righting reactions and moved the mean position on the x-axis (COPx) to the right and the mean position on the y-axis (COPy) to the front. During the postural righting reaction towards the right side, RC-GVS induced resistance against the righting reaction, COPx was deflected to the right, COPy was deflected backward, and the angle of the neck tilt increased. The findings revealed that GVS with anodal stimulation on the paralysed side could promote righting reactions in patients with post-stroke hemiplegia. Significance StatementThe study findings suggest that using the contralesional placement of the anode promotes righting reactions, and galvanic vestibular stimulation can induce joint movements in the neck and trunk by polarising it to act as resistance against righting reactions.

Numerical study on the mixed convection with nanofluids in vertical channel asymmetrically heated

Mixed convection heat transfer in cavities is of great interest in many industrial applications, such as the development of crystals, the thermal control of electronic components, the nuclear reactors and various manufacturing processes. Components are generally located on the wall of a channel, that can be also tilted and their thermal control is carried out by the fluid flow. They can be schematized as thermal sources on vertical boards and the heat flux is removed by natural or mixed convection. As to the mixed convection, the interaction between the buoyancy forces and the external flow plays a significant role in the thermal design of systems. When natural convection is not strong enough to remove heat flux, mixed convection is adoptedIn particular, mixed convection due to moving surfaces is very important is these applications. Mixed convection because of buoyancy and motion of one of the channel walls has received little research attention and few guidelines are available for choosing the best performing channel configuration. Moreover, to optimize the transfer through natural convection, it is possible to modify the geometric parameters of the component, thus maximizing the convective heat transfer coefficient. If this is not possible or if one chooses to keep the geometry of the component unchanged for design choices, a possible alternative is the use of nanofluids. The properties of nanofluids exhibit a behaviour ranging between the properties of the base fluid and the properties of the nanoparticles. However, the addition of nanoparticles in the working fluid is considered to enhance the thermal behaviour of the base fluid. In this study a numerical investigation of mixed convection in nanofluids due to the interaction between a buoyancy flow and a moving plate induced flow in a vertical channel is carried out. The moving plate has a constant velocity and moves in the same direction with respect to the buoyancy force. The channel principal walls are heated with uniform heat flux. The numerical analysis is obtained by means of the commercial code Fluent. The effects of the different wall heat fluxes and moving plate velocities are investigated and results in terms of the channel wall and moving plate temperatures and Nusselt numbers are given.

Experimental study on burn-through behavior of vertical wood board in the early fire stage

Experimental study on burn-through behavior of vertical wood board in the early fire stage

Detection and Localization of Thin Vertical Board for UAV Perching

An autonomous vision-based landing system with a passively driven perching mechanism for a UAV is described in this paper. In our previous research, we developed a passively driven perching mechanism that can land on various shapes. The goal of this study was to achieve automatic perching on a thin vertical board using the passive mechanism. For autonomous perching, an RGB-D camera was used to detect and track a perching target and automatically control the flight of the UAV to the target position. The combination of RGB-D tracking system for thin vertical board and self-position estimation from another tracking camera mounted on the UAV enabled automatic perching. The results of the experiment using the passively driven perching mechanism and autonomous system verified that it is possible to land on objects such as road signs at heights, by using the integrated system for object detection and UAV control. In the experiment, the UAV was controlled to fly autonomously to the vicinity of the target and then perched on a 2 mm thick board.

Experimental investigations on transient burning characteristics of a butt-jointed wooden wall with horizontal gaps in timber buildings

In this paper, a series of experiments were carried out to study transient burning behaviors of vertical wooden boards widely used as dividing walls in timber buildings. The boards were butt-jointed by wood battens, forming several horizontal gaps. Gap sizes were carefully controlled as 0 mm, 2 mm and 5 mm to study their effects on the burning process. The boards were heated with one surface initially exposed to fire, and heat release rates (HRRs) of fire source were set from 5 kW to 15 kW to simulate the early fire stage. Results showed that there existed a transition from single-sided burning to double-sided burning for wooden boards exposed to fire. The start of the double-sided burning was accompanied with sharp increases in HRR and temperature. With the increase of the gap size, the start time for double-sided burning was obviously shortened, and the role of gap was analyzed as strengthening heat convection and air entrainment. A simplified estimation method for transient HRR during the whole burning process was put forward, which agreed well with the experiments. This work supports guidance to predict fire development in timber buildings in the early fire stage.

Design and Application of a Novel Silicone Nasal Implant.

Traditional silicone implants used in augmentation rhinoplasty lead to postoperative complications. To introduce a novel silicone implant designed to reduce postoperative complications. The author designed a novel modification for the traditional silicone nasal implant, which has a particle surface, vertical and horizontal grooves, and a special vertical board to support the nasal tip. A total of 114 consecutive clinical cases were retrospectively reviewed from September 2016 to November 2022, with a minimum of 36 months and an average 51 months of follow-up. All patients underwent augmentation rhinoplasty using this novel implant, with 97 (85.09%) patients using only the silicone and 17 (14.91%) the silicone implant with conchal cartilage. Surgical complications such as sliding down, redness, extrusion, deviation, translucency, capsular contracture, or infection were recorded. The median patient age was 28 (range, 18-55) years, with 109 female and 5 male patients. Among the 114 cases, 46 (40.35%) involved primary surgery and 68 (59.65%) involved revisional surgery. The overall complication rate was 4.39%, and 0.88% of the patients had slight redness, 0.88% had intermittent pain, and 2.63% had infections. No other complication was observed, and all complications occurred in revisional surgeries. A total of 109 patients (95.61%) showed satisfying results without any postoperative complication. None of the patients with primary surgery reported postoperative complications. The novel silicone nasal implant can effectively reduce the rate of postoperative complications. Therefore, augmentation rhinoplasty using this implant enables a more natural-looking outcome.

Intra- and inter-rater reliability of angle assessment for righting reaction from a tilted sitting position in healthy participants.

[Purpose] Lateral balance and the righting reaction are related to trunk function and many activities of daily living. However, there are no studies evaluating the assessment of the righting reaction while ensuring safety. This study aimed to clarify the reliability of assessments for the righting reaction from a tilted sitting position in healthy participants. [Participants and Methods] The participants of this study included 28 healthy young adults. Before the start of the study, markers were attached to the participants for data collection. Participants were asked to sit on a vertical board, tilted 10 degrees, and were asked to perform the righting reaction. This test was repeated four times on each side. The actions were recorded with a video camera, and two analysts used the Image J software to calculate the angles of the righting reaction of the neck, trunk, and left and right lower legs. [Results] High reliability was obtained regardless of the tilt direction and site of righting reaction. In addition, no adverse events occurred. [Conclusion] It was possible to evaluate the righting reaction while ensuring safety, and reproducibility was confirmed.

Aerodynamic characteristics of the train–SENB (semi-enclosed noise barrier) system: A high-speed model experiment and LES study

The aerodynamic effect of a passing high-speed train (HST) may cause structural damage to the semi-enclosed noise barrier (SENB). Moreover, the rapid variation of the aerodynamic environment may deteriorate the operation stability of the train and passenger comfort. Three types of rectangular SENBs, namely, inverted-L-shaped noise barriers installed on double-line railways (ILSNB-DL), inverted-L-shaped noise barriers with a vertical board installed on double-line railways (ILSNBVB-DL) and inverted-L-shaped noise barriers with a vertical board installed on single-line railways (ILSNBVB-SL), are considered in this research. By establishing a 1:16.8 train–SENB moving-model system and a corresponding large eddy simulation (LES) model, the time-history and spatial characteristics, flow field mechanism and spectral characteristics of the aerodynamic pressure acting on the three types of SENBs are investigated. Moreover, the differences in the time-history characteristic, flow field mechanism and spectral characteristic of the aerodynamic loads on the HST when passing through the three types of SENBs are also compared. The aerodynamic pressure inside ILSNBVB-DL is more than 27% higher than that of ILSNB-DL, and the aerodynamic pressure inside ILSNBVB-SL is more than 16% higher than that of ILSNBVB-DL. When the HST enters and exits ILSNBVB-SL, the area with positive and negative pressure on the train surface varies the most dramatically, causing the amplitude of the lift force of the HST when passing through ILSNBVB-SL being approximately four times the value when the HST passes through ILSNB-DL and ILSNBVB-DL. When the HST enters and exits ILSNB-DL and ILSNBVB-DL, the pressure difference between the two sides of the HST is greater than that when the HST enters and exits ILSNBVB-SL, leading to the maximum amplitude of the side force of the HST passing through ILSNB-DL being 1.8 times of the value for ILSNBVB-DL and ILSNBVB-SL.

Numerical studies on conjugate convection from discretely heated electronic board

PurposeThis paper deals with numerical studies into combined conduction, convection and radiation from a heated vertical electronic board are provided here.Design/methodology/approachHere three inbuilt heaters with decrease in their heights were placed in the vertical electronic board. With respect to the non-heat portions, two configurations were studied. The first considers the non-heat portions to be adiabatic, while in the second, they are non-adiabatic. The heat that is produced in three heaters is conducted along the board and is dissipated either from the heater portions alone or from the whole board by convection and radiation. Air is considered as working medium, while the equations of heat transfer and flow of fluid are handled without boundary layer approximations. These equations were further solved using finite volume method with Gauss–Seidel iteration method.FindingsResults of various comparative studies were discussed to bring out the relevance of thermal conductivity, modified Richardson number and surface emissivity on different heat transfer and flow results concerning this problem.Originality/valueThe optimum values of surface emissivity, thermal conductivity and modified Richardson number have also been notionally explored.

Anisothermal flow dynamics in ventilated open space involved with indoor comfort

Energy cooling systems or thermal buildings are increasingly fertile subject for reducing the energy demand or for the indoor air quality coupled with energy demand. This work is devoted to studying cooling ability within an open domain. The space model is considered as a cavity heated on one external sidewall and cooled by three vertical boards which separate the room into four sub-domains. A complex flow structure is obtained in the present “cooperating” case, in which dynamic and buoyancy forces are added together on the active wall. It shows that the natural convection and the forced flow (injection) act directly on the resulting patterns, heat exchange, mixing ability, which control the thermal field homogeneity and the cooling necessity. The computation results show the influence of the parameters and the vertical boards on heat transfer in the enclosure. Under the wide range of Rayleigh (Ra) and Reynolds (Re) numbers, the features of dynamic and thermal fields permit to categorize the different convection phenomena. The intensity of mixing was quantified versus Ra and Re and we find the conditions and threshold of the different domains (diffusive, natural, forced and mixed convection).

The Neural Control Mechanisms of Gekkonid Adhesion Locomotion: The Effect of Spinal Cord Lesions

Objective: the role of the supraspinal system in the neural control mechanisms of adhesion locomotor pattern formation was studied in lizard Gekko gecko. Methods: the locomotor performance and adaptation of the chronically lesioned Gekko gecko was documented before and after either partial or complete spinal lesions. They were filmed moving on a flat and smooth platform that was inclined at 0°, ±45°, and ±90°, as well as the horizontal mats and the vertical oak background board in the terraria, to evaluate locomotor functional recovery. The geckos were also tested on the platform by two half and nose-up or -down rotations in steps of 15° throughout 180° to investigate the recovery of the ability to respond dynamically to external perturbations. Results: after relatively small lesions of a hemisection, the locomotor performance was largely indistinguishable from that before and after a sham operation. During the initial period of recovery after the largest lesions of a dorsal or a ventral hemisection within 1 wk, the geckos behaved essentially as the complete spinal geckos, while permanent deficits in locomotor performance remained and did not decrease afterwards for ≥6 mth. Conclusions: by analyzing the correlation among locomotor performances, and between locomotor performances and spinal cord lesions, we suggest that the dorsal spinal pathways and ventral spinal pathways participate, respectively, in the control of the limb coupling, and in the deployment and the detachment of the adhesive apparatus. The present study will provide certain neurobiological guidance for the design of bio-robots, as well as sprawling robots inspired by the geckos.

Aerosol morphology and particle size distribution in orthopaedic bone machining: a laboratory worst-case contamination simulation. Is high-speed bone machining potentially harmful by pollution and quality schemes and what measures could be taken for prevention?

Aim of the studyHigh-speed bone machining devices with irrigation fluid were used in surgery to spread aerosols and toss tissue particles of varying morphology into the operating room. Based on measurements taken on a phantom object, the shape, size, and spatial contamination distribution of such particles were assessed.MethodCadaveric femoral heads were continuously machined with a spherical bur, manually held at a fixed attack angle. The irrigation fluid used during bone machining was enriched with bacteria to act as a tracer to quantify the spatial contamination. A vertical board equipped with snippets served as a phantom object to assess contamination load and morphology of airborne particles.ResultsEight-nine percent of the particles had a non-circular cross section. The detected particle size ranged across six orders of magnitude, from 0.006 to 4 mm2 with a median particle size of 0.125 mm2. The CFU counts observed after the standard machining time ranged from 7 to 240, with a median of 2 CFUs. The highest median contamination was seen at the upper right corner of the phantom.DiscussionThe experiments show that contaminating particles of a wide variety of shapes and sizes are part of the aerosol created by high-speed burring. While protection of personnel and equipment is always important, surgical helmets should be worn, especially at contamination hotspots, and gloves should be replaced at the end of machining. Sensitive instruments and measuring devices—such as optical sensors—should also be protected effectively, as the optical measurement may be obstructed by aerosol particles.

The EFFECT OF JUMP TO BOX EXERCISES AS HIGH 30 CM AND 40 CM ON THE LEG MUSCLES POWER VOLLEYBALL PLAYERS GOVITA SEMARANG

The purpose of this study: 1) To find out the effect of jump to box exercise as high 30 cm on leg muscle power of Govita Volleyball Players Semarang, 2) To find out the effect of jump to box exercise as high 40 cm on leg muscle power of Govita Volleyball Players Semarang, 3) To find out the difference effect of jump to box exercise as high 30 cm and 40 cm on leg muscle power of Govita Semarang Volleyball Player. This research is using 16 women volleyball players Govita Semarang with range on age 13-15 years to be sample. The research design using a match subject design, the group division using the subject matched ordinal pairing formula A-B-B-A. Test instrument used a vertical jump test with a vertical board. Data analysis use a pair sample t-test to test the hypothesis. The results of this study: 1) There have an effect of jump to box exercise as high 30 cm on leg muscle power of Govita Semarang Volleyball Player with the result tcount (3,989) > ttable (2,364), 2) There have an effect of jump to box exercise as high 40 cm on leg muscle power of the Govita Semarang Volleyball Player with the result tcount (4,518) > ttable (2,364) , 3) Both result have same effect of leg muscle power of the Govita Volleyball Players Semarang, with difference result tcount (1,432) < ttable (2,364). The conclusions are: 1) There have an effect of 30 cm high jump to box exercise on leg muscle power of Govita Volleyball players in Semarang, 2) There have an effect of 40 cm high jump to box exercise on the leg muscle power of the Govita Volleyball players in Semarang, 3) Both exercises have the same effect on the results of the leg muscle power of the Govita Volleyball players in Semarang. For the future researchers who isinterested to do the same research, they can adding a control group comparison.

Feasibility of Using a Commercial Board Game to Assess Upper Extremity Function in Older Adults

Upper extremity function, particularly the hand, declines with aging and is predictive of executive ability and independence. Standard assessments typically focus on strength partly due to a lack of easily administered functional tasks requiring multi-joint coordination and precision grasp. This study aimed to determine the feasibility of using an inexpensive board game to assess upper extremity function in older adults. Six healthy older adults (77 +/- 5.1 years) completed reaching tasks using the Connect4® game that requires grasping and placing small discs into a vertical board. Tasks included different hand configurations (unilateral, bilateral), and two dual-task conditions (serial subtraction by 7s and placing colored discs to match specific color patterns). The time to complete each task was recorded. For comparison purposes, participants completed a standardized pegboard test (Purdue Pegboard) using one or both hands. Connect4 results were similar to age-normative findings reported for the Purdue Pegboard. Dominant versus non-dominant hand performance did not differ while bilateral coordination tasks were slower than unilateral tasks for both the Purdue Pegboard (p<0.05) and Connect4 (p<0.01). Pegboard and Connect4 times were moderately to strongly correlated for all hand configurations. Dual-task conditions using Connect4 led to longer completion times (p<0.05). Preliminary results support the use of Connect4 as a functional upper extremity assessment tool for older adults. It is inexpensive, engaging, easy to use, and allows for cognitive-motor assessment using dual-task protocols, a critical factor in maintaining functional independence in older individuals. Further research will include a formal validation study across a wider age range.

Millimeter-Wave 2-D Beam-Switchable and Scalable Phased Antenna Array

This communication proposes a millimeter-wave (mmWave) phased antenna array configuration, with 2-D beam-switching functionality and scalability in terms of the array size and number of switchable beams. A wideband vertically installed planar transition (VIPT) works in conjunction with a flexible substrate to implement a two-stage Rotman lens and to simultaneously increase the scalability and integration space without requiring expensive RF cables and connectors. In addition, owing to the VIPT, the vertical board can be considered a replaceable component and can be replaced by different designs to satisfy different applications. Prototypes of 60 GHz phased antenna array are manufactured and measured. The measurement results confirm that the proposed array configuration can implement 32 different main beam directions with a coverage angle of 70° in terms of both elevation and azimuth. The proposed configuration is a feasible and promising approach for mmWave radio applications.

Novel twelve port eight element UWB‐MIMO antenna

AbstractThis article presents the design of a highly integrated twelve port ultra‐wideband (UWB) antenna array for multiple‐input multiple‐output (MIMO) communications. The proposed array consists of a unit cell element constructed using a circular arc structure excited by a simple microstrip line feed terminated by an arc‐like stub. The proposed unit cell antenna covers 3–9 GHz covering most of the third, fourth, and fifth generation communication frequencies. The 3D antenna array has an overall board size of 33 × 33 × 15 mm3 consisting of one horizontal board and two vertical boards. The vertical boards are interlocked and are directly positioned above the horizontal boards. Four antennas with dual feed excitation are deployed on the horizontal board while each vertical board is printed with two elements with single port excitation. Thus, a highly integrated twelve port antenna is realized with isolation better than 15 dB between each port. The prototype antenna offers both polarization and pattern diversity leading to enhanced MIMO performance.

Deployable Rigid-Flexible Tightly Coupled Dipole Array (RF-TCDA)

An origami-based Tightly Coupled Dipole Array (TCDA) is proposed for small satellite applications. The array is formed by a two-layered structure using rigid and flexible substrates to enable accordion-like folding. The proposed TCDA operates across 0.4-2.4 GHz with VSWR < 3 at broadside and across 0.6-2.4 GHz with VSWR < 3 when scanning down to 45∘ in the E-, D-, and H-plane. An 8 × 8 prototype was fabricated using Kapton Polyimide and FR4 and tested to verify the bandwidth and gain of the origami array. The fabricated prototype was demonstrated to be packable, low-profile, and lightweight (only 1.1kg). Notably, when packed, the array has a one-dimensional size reduction of 75%. As will be discussed, the packing compression is made possible by eliminating vertical PCB boards and incorporating the balun feeds within the dipole layer. To our knowledge, this is one of the first foldable, low profile, and low-scanning ultra-wideband arrays in the literature.

Numerical modelling of climate-induced fracture and deformation in wood: Application to historical museum objects

Damage in oak wood museum objects under indoor climate variations (relative humidity, temperature) is studied using a thermo-hygro-mechanical model. The model incorporates the effects of moisture sorption hysteresis and discrete cracking, and is implemented within a finite element framework using a staggered update procedure. Sorption experiments were performed in order to calibrate the moisture sorption hysteresis model. The basic features of the coupled formulation are stepwisely demonstrated by solving the response of a basic oak wood specimen under a sequence of thermo-hygro-mechanical loading conditions of increasing complexity. These simulations show that the deformation and fracture generated by thermal variations representative of indoor museum conditions are minor compared to the contributions caused by relative humidity variations. Subsequently, the hygro-mechanical response of an oak wood cabinet door panel is analysed under a drop in relative humidity from 60% to 20%, and the results are compared to those obtained by experiments. The numerical and experimental results are in good agreement, and indicate that at the connection between the cleated end and the vertical boards the restrained hygric shrinkage is maximal, which stimulates local crack development. The susceptibility to fracture only becomes activated after the oak wood has reached a certain age, as the effect of aging induces a decrease of the oak wood tensile strength perpendicular to the grain direction with time. Further, when the initial moisture content lies on the desorption boundary curve, the amount of fracture generated is larger compared to when it lies on the adsorption boundary curve. Also, fracture only nucleates after a specific drop in relative humidity, whereby the crack growth under a continuous decrease in relative humidity initially develops relatively fast, but at a certain stage decreases substantially and becomes (almost) zero when reaching a fully developed failure crack. The location and orientation of this failure crack are in accordance with in situ observations on historical oak wood cabinets.

Experimental investigation of substrate board orientation effect on the optimal distribution of IC chips under forced convection

ABSTRACT Steady-state experiments are conducted under the laminar forced convection heat transfer mode for the cooling of seven asymmetric IC chips (heat sources) mounted at different positions on the substrate board. The board is oriented at different angles, i.e., at 0° (horizontal), 30°, 60°, and 90° (vertical) to study its effect on the cooling of the IC chips. The goal is to determine the optimum configuration (arrangement of these seven IC chips on the board) leading to minimize their maximum temperature. The optimal configuration is determined by employing a hybrid optimization strategy that combines the Artificial neural network (ANN) with Genetic algorithm (GA) which is further validated with suitable experiments. Different correlations are proposed to study the effect of the substrate board orientation on the Nusselt number (cooling rate) and temperature of the IC chips. The results suggest that the temperature of the IC chips is a strong function of their size, positioning on the substrate board, input heat flux, and the substrate board orientation. The temperature of the IC chips is least for the 30° oriented board, as for this case, the maximum surface area of the board is in contact with the flowing air. This helps in cooling the chips effectively in lowering their temperature. The surface area available to dissipate the heat from the IC chips keeps on decreasing after the 30°. For the vertical orientation, the air entering the inlet section of the substrate board hits perpendicular to it. Hence, the temperature of the IC chips is maximum for the vertical substrate board. Air velocity is also crucial for the cooling of the IC chips. There is a temperature drop of 1.42–17.33% for the higher velocity (8 m/s) as compared to the lower one (4.5 m/s).