Half Scale Research Articles

Prototype high voltage bushing: Configuration to its operational demonstration

High Voltage Bushing (HVB) is the key component of Diagnostic Neutral Beam (DNB) system of ITER as it provides access to high voltage electrical, hydraulic, gas and diagnostic feedlines to the beam source with isolation from grounded vessel. HVB also provides primary vacuum confinement for the DNB system. Being Safety Important Class (SIC) component of ITER, it involves several configurational, technological and operational challenges. To ensure its operational performance & reliability, particularly electrostatic behavior, half scale down Prototype High Voltage Bushing (PHVB) is designed considering same design criteria of DNB HVB. Design optimization has been carried out followed by finite element (FE) analysis to obtain DNB HVB equivalent electric stress on different parts of PHVB, taking into account all design, manufacturing & space constraints. PHVB was tested up to 60kV without breakdown, which validates its design for the envisaged operation of 50kV DC. This paper presents the design of PHVB, FEA validation, manufacturing constraints, experimental layout with interfacing auxiliary systems and operational results related to functional performance.

Seismic Column-to-Footing Connections Using Grouted Splice Sleeves

Mechanical couplers have been used in connections between prefabricated reinforced concrete elements. Grouted splice sleeves offer good construction tolerance and a bond related load transfer mechanism between the connecting members. The present study investigates the seismic performance of grouted splice sleeve connections with the connectors placed in the column or footing of bridge subassemblies, and intentional debonding of the footing dowel bars. Quasi static cyclic loads were used to test three half scale precast column to footing specimens and one cast in place control specimen. The precast concrete specimens incorporated grouted splice sleeve connectors in which two bars were grouted at both ends. Experimental results show that the precast subassemblies had a lower displacement ductility capacity than the control specimen. Improved seismic response was observed when the splice sleeve connectors were located inside the footing rather than the column end. An intentional debonded reinforcing bar zone was used to further improve the displacement ductility capacity of the bridge subassembly.

Structural behavior of strengthening masonry in-filled frames subjected to lateral load using bonded and un-bonded CFRP

Lateral loads annually destroy many reinforced concrete structures in different countries. However, there is a necessary need to retrofit masonry infill walls to utilize them as lateral load resisting elements. For this purpose, an experimental program has been carried out on half scale specimens to characterize the behavior of single story brick masonry in-filled frames under the effect of lateral loads. The effectiveness of different strengthening techniques is investigated using Carbon–fiber Reinforcement Polymer (CFRP). The steel reinforcement at the beam-columns joints of all specimens was detailed as hinged connection. FRP sheets and FRP strips were used as strengthening agents for the tested specimens. They were utilized in two different cases, bonded or unbonded to the masonry wall. In addition, the FRP anchor technique was used to increase the efficiency of bonding the strengthening agents with the frames and the walls. The load–displacement behavior, FRP strain, crack pattern, steel strain, and mode of failure of the tested specimens were investigated. The results showed that the used strengthening methods are effective, with high increase in strength and ductility. In addition, an analytical model was presented and solved. Based on this model, simplified empirical equation to design the required amount of FRP needed to resist lateral loads was proposed. The equation showed a good agreement with both the experimental result and finite element output.

Shaking table test of fibre reinforced masonry walls under out-of-plane loading

The present paper describes an experimental procedure to study the effect of retrofitting technique using fibre reinforced composites on the out-of-plane seismic performance of masonry walls. For this purpose, three “I” shaped half scale bearing masonry walls were tested under scaled versions of Bam, Kobe and Northridge earthquake horizontal components using one degree shaking table equipment. Each specimen is loaded axially by a concrete beam to simulate the effect of scaling; also two transverse walls are used to prevent overturning of the main wall against out-of-plane loads. The subject of this study is mainly about dynamic response of FRP strengthened masonry walls in terms of fundamental frequency, displacement capacity, shear strength, crack patterns and energy absorption. Experimental results revealed that FRP reinforcement can significantly improve masonry walls performance.

Design of PC beam-column joint applied X-braced bars in the segmented structural system

This study suggests a joint design using an X-brace bar to identify the stability and structural performance of a precast concrete (PC) beam-column joint design, which may cause problems when used in a segmented PC beam system for a long-span structure. For this, an experimental PC beam-column model at half scale was designed and veri­fied for applicability of X-braced bars in a panel zone. While previous studies suggested the development of a long-span structural system using precast concrete (PC) and described the problems with PC beam-column joints, this study proposes a solution to improve the structural stability and performance of a PC beam-column joint design and conducts analytical verification.

In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging.

Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment.

Improved Anatomical Specificity of Non-invasive Neuro-stimulation by High Frequency (5 MHz) Ultrasound.

Low frequency ultrasound (<1 MHz) has been demonstrated to be a promising approach for non-invasive neuro-stimulation. However, the focal width is limited to be half centimeter scale. Minimizing the stimulation region with higher frequency ultrasound will provide a great opportunity to expand its application. This study first time examines the feasibility of using high frequency (5 MHz) ultrasound to achieve neuro-stimulation in brain, and verifies the anatomical specificity of neuro-stimulation in vivo. 1 MHz and 5 MHz ultrasound stimulation were evaluated in the same group of mice. Electromyography (EMG) collected from tail muscles together with the motion response videos were analyzed for evaluating the stimulation effects. Our results indicate that 5 MHz ultrasound can successfully achieve neuro-stimulation. The equivalent diameter (ED) of the stimulation region with 5 MHz ultrasound (0.29 ± 0.08 mm) is significantly smaller than that with 1 MHz (0.83 ± 0.11 mm). The response latency of 5 MHz ultrasound (45 ± 31 ms) is also shorter than that of 1 MHz ultrasound (208 ± 111 ms). Consequently, high frequency (5 MHz) ultrasound can successfully activate the brain circuits in mice. It provides a smaller stimulation region, which offers improved anatomical specificity for neuro-stimulation in a non-invasive manner.

Far field prediction of sound pressure level using panel contribution analysis and scale modeling

Panel contribution analysis is reviewed and then utilized to predict the sound radiation from a generator set. The generator set is divided into patches and transfer functions between the sound pressure at a point in the far field and the velocity of a patch were determined reciprocally both for the full-scale structure and a half-scale model. With the generator set running, a P-U probe was used to measure particle velocity and sound intensity simultaneously on each patch. The sound pressure level at a receiver point located 4.9 m away from the side of the generator set was calculated assuming uncorrelated and correlated sources. The predicted sound pressure, based on both full and half scale models, compared well with that measured. Transfer functions were also determined using boundary element methods and compared well with measurement. In addition, the contributions from each surface of the generator set enclosure were determined.

Value locality based storage compression memory architecture for ECG sensor node

This paper proposes a value compression memory architecture for QRS detection in ultra-low-power ECG sensor nodes. Based on the exploration of value spatial locality in the most critical preprocessing stage of the ECG algorithm, a cost efficient compression strategy, which reorganizes several adjacent sample values into a base value with several displacements, is proposed. The displacements will be half or quarter scale quantifications; as a result, the storage size is reduced. The memory architecture saves memory space by storing compressed data with value spatial locality into a compressed memory section and by using a small, uncompressed memory section as backup to store the uncompressed data when a value spatial locality miss occurs. Furthermore, a low-power accession strategy is proposed to achieve low-power accession. An embodiment of the proposed memory architecture has been evaluated using the MIT/BIH database, the proposed memory architecture and a low-power accession strategy to achieve memory space savings of 32.5% and to achieve a 68.1% power reduction with a negligible performance reduction of 0.2%.

Behavior of interior RC wide and conventional beam-column roof joints under cyclic load

Performance of RC interior beam-column joints at roof level is defined as the area needing research by ACI 352R-02. Because of a lack of research data on performance of this type of joints, two half scale interior beam-column connections with discontinuous column were designed in accordance with ACI 318-11 and ACI 352R-02 provisions. One of the specimens had wide beams and the other had conventional beams to compare their behavior. These specimens were tested under quasi-static cyclic loading. It became clear by the experiments that roof wide beam-column joint had lower strength compared to that of roof conventional beam-column joint. Both of the specimens had almost equal energy dissipation capacity. The conventional beam-column joint reached its expected capacity but wide beam-column joint did not reach its capacity. Moreover, wide beam-column joint had sufficient joint shear strength unlike conventional one. Therefore, joint shear requirements could be relaxed for roof wide beam-column joint. This relaxation must be reapproved by more tests to be advisable for design purposes.

1C33 水泳ヒューマノイドロボットSWUMANOIDによるバタフライ泳

The swimming humanoid robot "SWUMANOID" was developed in the previous study for research of human swimming. The crawl stroke and breaststroke have been already realized by the robot. However, the butterfly stroke has not been realized to date. Therefore, the objective of this study was to realize the free swimming of the butterfly stroke with the robot. The robot were developed on a half scale, and had 24 specially waterproofed motors inside the body. The swimming motion of butterfly stroke was created and examined by means of the simulation. The swimming experiment was conducted at a swimming pool. The swimming motion was filmed by a video camera. The swimming speed was estimated from the filmed images. As a result, the constant propulsion by the robot was confirmed. The swimming speed in the experiment was found to be 0.17〜0.20 m/s for the stroke cycle of 3.5 s. It was somewhat lower than that in the simulation.

From lab to full scale Active Flow Control drag reduction: How to bridge the gap?

Active Flow Control (AFC) is being investigated as a tool for boundary layer separation delay. Increasing lift by delaying stall has been the most common objective. More recently AFC is also being studied for drag reduction and mitigation of unsteadiness, resulting from massively separated flows. As such, fuel savings of heavy ground vehicles, while challenging, is a worthy task due to the huge economic, environmental and political impact. This paper describes a series of experiments aimed at increasing the base pressure on the trailer-end of a large truck–trailer configuration driving at highway speeds. In parallel to fundamental studies, not reviewed here for brevity, two road test campaigns were completed; a half scale wind tunnel test and smaller scale generic vehicle model wind tunnel experiments are described and analyzed. The method currently uses a 1/4 cylinder shaped rear-end mounted add-on device in which an array of synchronized Suction and Oscillatory blowing (SaOB) actuators is mounted. The passive as well as active effects of the steady suction and unsteady sideways-oscillating blowing are documented and careful experimentation allows the energy budget to be directly calculated from wind tunnel experiments. Good agreement between road tests and scaled tunnel model tests was found on the path to product development.

Experimental study of extreme thrust on a tidal stream rotor due to turbulent flow and with opposing waves

Time-varying thrust has been measured on a rotor in shallow turbulent flow at laboratory scale. The onset flow has a turbulence intensity of 12% at mid depth and a longitudinal turbulence length scale of half the depth, about 5 times the vertical scale, typical of shallow flows. The rotor is designed to have thrust and power coefficient variations with tip speed ratio close to that of a full-scale turbine. Three extreme probability distributions give similar thrust exceedance values with the Type 1 Pareto in mid range which gives 1:100, 1:1000 and 1:10000 exceedance thrust forces of 1.38, 1.5 and 1.59 times the mean value. With opposing waves superimposed the extreme thrust distribution has a very similar distribution to the turbulent flow only. Exceedance forces are predicted by superposition of a drag force with drag coefficient of 2.0 based on the wave particle velocity only and with an unchanged mean thrust coefficient of 0.89. These values are relevant for the design of support structures for marine turbines.

Preliminary Research on Rotating Icing Test Scaling Law

A rotating icing scaling law used for parameter selection for tests in an icing wind tunnel is established using the basic physical process of icing. The method of selecting parameters for a scale model of rotating components is also discussed. A dimensionless quantity, called the rotation number, is derived from the water film momentum equation in the rotating coordinate system. This parameter must be matched between the reference and the scale model. Water collection properties and ice accretion are numerical calculated through the similarity law established in this study to evaluate the effectiveness of the rotating icing similarity law. Results show that when the rotating speed of the full size cone is 1000 or 3000 r/min, nearly identical droplets collection features and ice shape can be obtained for the half scale model. Thus, the established rotating icing similarity law is effective and can be used as the theoretical guidance for parameter selection for ice wind tunnel tests.

Development of scaling laws of heat removal and CFD assessment in concrete cask air path

This study investigates heat transfer in a concrete cask such as one used at intermediate storage facilities of PWR spent fuels. Sufficient removal of decay heat is necessary not to damage fuel cladding that functions as a radioactive materials barrier. The experimental design parameters were derived in the half-scale model for the assessment of the design analysis methodology including a CFD tool. The scaling methodology was developed to design the half-scale model of the concrete cask in the spent fuel dry storage through scaling analysis. As one of the most important scaling laws, the requirement of similarity was selected for the temperature rise between the inlet and the exit in the air path. Based on the natural circulation in the channel, the scaling law was derived for total canister power maintaining the similarity of the temperature rise. Then, the temperature calculation and the flow analysis were performed in concrete cask facilities for the prototype and the half scale model using Computational Fluid Dynamics code. Through the CFD simulations, the similarity of the temperature rise was demonstrated well between the inlet and the exit, and the exit temperature was well maintained between the prototype and the half scale model. Also the scaling ratios of air mass flow rate and exit velocity obtained by the scaling analysis were in good agreement with those predicted by CFD analysis.

Strengthening of RC-Brick Masonry Walls with Opening Using Basalt Fiber Reinforced Polymer

FRP strengthening technique provides a promising alternative for masonry structures. This paper presents research results of quasi-static tests investigating the in-plane mechanical behavior of RC-brick masonry walls with opening strengthened with basalt fiber reinforced polymer (BFRP). Two half scale RC-brick walls were constructed, one without any strengthening scheme served as the reference specimen, another one was directly strengthened with BFRP in mixed strengthening configuration. All specimens were tested under low frequency cyclic loading. BFRP can effectively improve the lateral strength of the wall by a factor of 0.16, and the improvement in the lateral deformation capacity was much significant. The seismic performance of the composite wall strengthened with BFRP can exceed the unreinforced reference, which verifies the effectiveness of BFRP strengthening technique to strengthening RC-brick composite masonry structures in seismically endangered regions.

Effect of infill wall on the ductility and behavior of high strength reinforced concrete frames

This paper presents an experimental study for the behavior and ductility of H.S.R.C frames with infill wall under the effect of cyclic load. The experimental program was conducted on four specimens (frames). The parameters are studied change panel of frame from non infill to infill, change thickness of infill wall and change type of bricks. The dimension of frames is selected to represent half scale frames and tested under cyclic loading. All specimens of experimental program are tested in the reinforcement concrete testing laboratory at the Housing and Building National Research Center – Cairo.From the representation and the analysis of the obtained results, the main conclusions are pointed out; the lateral load resistance for infilled frames F2, F3 and F4 with infill wall (red bricks) thickness 12, 6cm and cement bricks 12cm, respectively was greater than the bare frame (F1) by about 184%, 61% and 99%, respectively. The ductility factor for infilled frames F2, F3 and F4 was less than the bare frame (F1) by about 57%, 51% and 46%, respectively.

Analysis of thermal problems in development of spent fuel transport cask for research reactors

A packaging for the transport of irradiated fuel from research reactors was designed by a group of researchers to improve the capability in the management of spent fuel elements from the reactors operated in the region. Two half scale models for MTR fuel were constructed and tested so far and a third one for both MTR and TRIGA fuels will be constructed and tested next. Four test campaigns have been carried out, covering both normal and hypothetical accident conditions of transportation. The thermal test is part of the requirements for the qualification of transportation packages for nuclear reactors spent fuel elements. In this paper, both the numerical modelling and experimental thermal tests performed are presented and discussed. The cask is briefly described as well as the finite element model developed and the main adopted hypotheses for the thermal phenomena. The results of both numerical runs and experimental tests are discussed as a tool to validate the thermal modelling. The impact limiters, attac...

Seismic Behavior Prediction of Flanged Unreinforced Masonry (FURM) Walls

In most available studies, unreinforced masonry (URM) walls are idealized as rectangular sections, while in reality walls have effective sectional shapes such as C, I, T, and L. In this article, the results of experimental and analytical assessment of flange effects on the behavior of I- and C-shaped URM walls are reported. Four clay brick walls at half scale were tested. Two specimens were designed with I- and C-shaped sections, and for comparison, two additional specimens were designed without flanges. The tests showed that under constant axial load the strength of the I-shaped wall increases, but that of the C-shaped wall decreases, because of out-of-plane distortion effects. Despite the loss of strength, both flanged walls indicated almost similar initial stiffness, deformation capacity, and mode of failure in comparison with walls without flanges. A mixed-mode analytical model is proposed to predict the lateral force displacement curve of flanged URM (FURM) walls. The proposed analytical model is based on section analysis of the walls and shows good agreement with previous experimental results.

Development and Initial Validation of the Observer-Rated Housing Quality Scale (OHQS) in a Multisite Trial of Housing First

Quality of housing has been shown to be related to health outcomes, including mental health and well-being, yet "objective" or observer-rated housing quality is rarely measured in housing intervention research. This may be due to a lack of standardized, reliable, and valid housing quality instruments. The objective of this research was to develop and validate the Observer-Rated Housing Quality Scale (OHQS) for use in a multisite trial of a "housing first" intervention for homeless individuals with mental illness. A list of 79 housing unit, building, and neighborhood characteristics was generated from a review of the relevant literature and three focus groups with consumers and housing service providers. The characteristics were then ranked by 47 researchers, consumers, and service providers on perceived importance, generalizability, universality of value, and evidence base. Items were then drafted, scaled (five points, half values allowed), and pretested in seven housing units and with seven raters using cognitive interviewing techniques. The draft scale was piloted in 55 housing units in Toronto and Winnipeg, Canada. Items were rated independently in each unit by two trained research assistants and a housing expert. Data were analyzed using classical psychometric approaches and intraclass correlation coefficients (ICC) for inter-rater reliability. The draft scale consisted of 34 items assessing three domains: the unit, the building, and the neighborhood. Five of 18 unit items and 3 of 7 building items displayed ceiling or floor effects and were adjusted accordingly. Internal consistency was very good (Cronbach's alpha = 0.90 for the unit items, 0.80 for the building items, and 0.92 total (unit and building)). Percent agreement ranged from 89 to 100% within one response scale value and 67 to 91% within one half scale value. Inter-rater reliability was also good (ICCs were 0.87 for the unit, 0.85 for the building, and 0.93 for the total scale). Three neighborhood items (e.g., distance to transit) were found to be most efficiently rated using publicly available information. The physical quality of housing can be reliably rated by trained but nonexpert raters using the OHQS. The tool has potential for improved measurement in housing-related health research, including addressing the limitations of self-report, and may also enable documenting the quality of housing that is provided by publicly funded housing programs.