Mono Block Research Articles

Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms

Assessing the performance of the ITER design for the tungsten (W) divertor Plasma Facing Units (PFUs) in a tokamak environment is a high priority issue to ensure efficient plasma operation. This paper reviews the most recent results derived from experiments and post-mortem analysis of the ITER-grade PFUs exposed in the WEST tokamak and the associated modelling, with a focus on understanding heat loading and damage evolution. Several shaping options, sharp or chamfered leading edge (LE), unshaped or shaped blocks with a toroidal bevel as foreseen in ITER, were investigated, under steady state heat fluxes of up to 120 MW⋅m−2 and 6 MW⋅m−2 on the sharp LE and top surface of the block, respectively. A very high spatial resolution (VHR) infrared (IR) camera (0.1 mm/pixel) was used to derive the temporal and surface distribution of the temperature and heat load on the castellated tungsten blocks for different geometric alignment and plasma conditions. Photonic modelling was required to reproduce the IR measurements in particular in the toroidal and poloidal gaps of the mono-block (MB) stacks where high apparent temperatures are observed. Specular reflection is found to be the dominant emitter in these parts of the blocks. W-cracking was observed on the leading edge of the blocks already within the first phase of plasma operation, during which the divertor was equipped with unshaped PFUs, including some intentionally misaligned blocks. Numerical analysis taking into account softening processes and mechanical stresses, revealed brittle failure due to transients as the dominant failure mechanisms. Ductile failure was observed in one particular block used for the melting experiment, therefore under extremely high steady state heat load conditions. W-melting achieved on actively cooled PFU exhibits specific features: shallow melting and slow melt displacement. Plasma exposure of pre-damaged PFUs at various damage levels (crack network and melted droplets) was carried out under high heat load conditions with several hours of cumulated plasma duration. IR data and preliminary surface analyses show no evidence of significant degradation damage progression under these conditions.

Infrared detection of tungsten cracking on actively cooled ITER-like component during high power experiment in WEST

The consequences of tungsten (W) damaging processes, such as cracking and melting, on divertor lifetime and plasma operation are high priority issues for ITER. A sustained melting experiment was conducted in WEST using a 2 mm deep groove geometry on the upstream mono-block (MB) to overexpose the sharp leading edge (LE) of the downstream MB. W-cracking has been evidenced for the first time with a very high spatial resolution infrared camera before tungsten melting was reached. These cracks develop when the monoblock temperature is about 2600 °C, thus higher than both ductile to brittle transition and softening threshold of tungsten, suggesting that these cracks are different from the ones observed in previous campaigns where brittle failure was involved, because of transient events on cold monoblock. Post-exposure analyses have been performed on the damaged monoblock, highlighting 12 main cracks on the LE, with a width varying from 33 µm to 77 µm, and an average spacing of 0.45 mm. Parallel heat flux about 90 MW/m2 has been derived from infrared temperature measurements, with a heat flux decay length on the target of 4 mm. The T-REX modelling code suggest here that with these thermal inputs, a crack can initiates due to thermal cycling without disruption, with a ductile failure, under 1 to 5 cycles for a tungsten DBTT varying from 400 °C to 500 °C.

Short and midterm functional and radiological outcomes of revision total hip arthroplasty with uncemented extensively porous coated monoblock cylindrical femoral stems

Background: This retrospective cohort study examines clinical and radiological outcomes of revision total hip arthroplasty (THA) using uncemented extensively porous coated mono block femoral stems. Methods: Patients who were operated for revision THA at medical college Baroda, between January 2008 to December 2018, and who had at least 36 months follow up were included in the study. Details were retrieved from hospital records. Harris hip score (HHS) was used for functional outcome and Paprosky classification was used for femoral bone defects. Results: Mean age of patients was 60.1 year (range 35-86 years), mean follow up was 84 months (range 40-126 months), Paprosky type 1 defect was found in 4 hips, type 2 was found in 20 hips and type 3a defect was found in 21 hips. Mean HHS improved from pre-operative 30 to post-operative 78 (p=0.0104). Expected survival at 5 and 10 years was more than 95%. No stem was loose at the end of follow up. Thigh pain and proximal osteolysis were most common complications. Conclusions: Extensively porous coated cylindrical stems give good functional and radiological outcomes at short and midterm follow up.

Evaluation of Dent aluation of Dentoskeletal and Phar eletal and Pharyngeal Air yngeal Airway Changes after y Changes after Treatment with Twin Block and Monoblock Appliance in Growing Patients

Objective: To compare of pharyngeal airway dimensions and dentoskeletal changes after treatment with twin block (TWB) and monoblock (MB) appliance in growing patients. Methods: The sample was comprised of a total of 72 patients at the ages of 10 to 13. The TWB group consisted of 36 patients (22 females, 14 males, mean age: 11.9±1.5) and MB group consisted of 36 patients (18 females, 18 males, mean age: 11.8±1.2). The linear and angular measurements were evaluated on lateral cephalometric radiographs at beginning (T0) and end of treatment (T1). Results: The amounts of increase in the inferior airway space, L1xNB, IMPA and FMA measurements from T0 to T1 in the TWB group were significantly higher (p < 0.05).In the TWB group, the amounts of the increase in the soft palate thickness, distance between hyoid and C3, Co-A and Co-Gn measurements from T0 to T1 in the female patients were significantly higher (p < 0.05).In the MB group, the amounts of increase in the Upper adenoid thickness and Vertical airway length measurements from T0 to T1 in the female patients were significantly higher (p < 0.05). Conclusion: Both the MB and TWB appliances increase the pharyngeal airway dimensions, and the lower airway is most affected by the appliance type. The effects of the MB and TWB appliances on tongue dimensions and hyoid bone movements are different.

Fuzzy Elliptic Curve Cryptography for Authentication in Internet of Things

The security and privacy of the network in Internet of Things (IoT) systems are becoming more critical as we are more dependent on smart systems. Considering that packets are exchanged between the end user and the sensing devices, it is then important to ensure the security, privacy, and integrity of the transmitted data by designing a secure and a lightweight authentication protocol for IoT systems. In this article, in order to improve the authentication and the encryption in IoT systems, we present a novel method of authentication and encryption based on elliptic curve cryptography (ECC) using random numbers generated by fuzzy logic. We evaluate our novel key generation method by using standard randomness tests, such as: frequency test, frequency test with mono block, run test, discrete Fourier transform (DFT) test, and advanced DFT test. Our results show superior performance compared to existing ECC based on shift registers. In addition, we apply some attack algorithms, such as Pollard’s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\rho $ </tex-math></inline-formula> and Baby-step Giant-step, to evaluate the vulnerability of the proposed scheme.

Pump performance improvement using DMAIC method for industrial application

In recent years, regenerative model pumps have become more interested in various commercial processes. Havells India Limited Produces regenerative water pumps which is mostly used in domestic application. Duration of assembly of regenerative water pump we found from the quality supervisors and production monthly data, a self-priming mono block regenerative pump (M1 model) have jamming issue. Due to this jamming of pump rejection is 20% of monthly production which is a major problem. For solving this problem, two techniques are used. The result of the project was to reduce the overall refusal rate in the production line from 20% to 2%, which enabled the production line to meet demand-using DMAIC. This analysis presents the current product improvement based on the DMAIC approach as a preferential method for defect identification and process improvement using various statistical tools such as the Cause and Effect Diagram.

Very high-resolution infrared imagery of misaligned tungsten monoblock edge heating in the WEST tokamak

Fourteen ITER-like plasma-facing units (PFUs) made of bulk tungsten were installed in the WEST tokamak divertor. Five of which were misaligned with their poloidal leading edges (LEs) exposed to the plasma heat flux: two sharp-edge PFUs and three chamfered PFUs (vertical misalignment h = 0.30 ± 0.1 mm). The parallel heat flux is measured on the outer strike point with a very high-resolution (VHR) infrared camera, featuring a sub-millimeter spatial resolution (~0.1 mm/pixel). A Medium Wavelength IR filter (MWIR) was used to lower the temperature detection threshold (Tthreshold,BB ≈ 250 °C) and extend the IR analysis to the full toroidal Monoblock (MB) length on both outer (OSP) and inner (ISP) strike points. The parallel heat flux derived from the VHR data (~70 MW/m2) is consistent with previous analysis and other measurements (Thermocouple and Fiber Bragg Grating) at the maximum heat flux location (OSP). This corresponds to real temperatures of about 1000 °C on the LE. Values obtained on the LE of the ISP are typically lower than of the OSP by a factor of two. However, a significant discrepancy between modeling and measurement is observed along with the toroidal temperature profile, with a temperature drop in the first 5 mm after the LEs. Visual and microscopic analysis performed on the component show clear evidence of surface state modification caused by plasma exposure: the presence of cracks on the LE, polished surface in its vicinity, and rougher surfaces further away from the LE.

Comparison of facial soft tissue changes after treatment with 3 different functional appliances

This study aimed to evaluate the effects of 3 different fixed or removable functional appliances on the soft tissue changes in patients with Class II Division 1 malocclusion using 3-dimensional images. A total of 60 patients with Class II Division 1 malocclusion (38 girls and 22 boys; mean age, 12.35±1.01years) were treated with 3 different functional appliances, namely, Twin-block (TB) (group TB, n=20), mono-block (MB) (group MB, n=20), or Herbst (H) (group H, n=20) for 9.55±1.46months. Three-dimensional photographs of each patient were taken at the baseline and the end of the therapy with a 3dMD Face system (3dMD, Atlanta, Ga). Statistical analyses were performed using the dependent samples t test, 1-way analysis of variance, Kruskal-Wallis, Mann-Whitney U, and Wilcoxon signed rank tests. No statistically significant differences were detected for soft tissue changes except for the lower facial width found, at least in group H (P<0.05). Volumetric differences in the mandible were similar between the groups (P>0.05). A statistically significant decrease in total facial height and an increase in convexity angle and facial depth were detected in all groups after treatment compared with the baseline (P<0.05). The upper and lower facial height, lower lip height, and nasal width were statistically significantly increased in the TB and MB groups after treatment compared with the baseline (P<0.05) and similar to those in group H (P>0.05). TB, MB, and H appliances may promote the facial soft tissue profile, including volumetric improvement, in the mandibular region.

PERFORMANCE EVALUATION OF END SUCTION, SINGLE STAGE, RADIAL DISCHARGE CENTRIFUGAL PUMP IN TURBINE MODE OPERATION

Pump as Turbine (PAT) provides a cost-effective alternative to conventional hydro turbines for high terrain rural areas where grid supply is not feasible. PAT technology is simple, low in cost and easy to harness. End suction centrifugal pumps are readily available as compared to conventional custom made hydro turbines. This paper presents theoretical, numerical and experimental study of radial discharge centrifugal pump in hydro turbine mode. Experimental setup is used to investigate performance of radial discharge end suction mono block centrifugal pump in pump and turbine mode and the results are compared with theoretical and numerical results. Performance characteristic of mono block pump of specific speed 20.28 (m, m3 /s) in turbine mode operation are determined through experiment. The experiment results reveal suitability of using a mono block centrifugal pump in hydro turbine mode. The results confirm that the pump in hydro turbine mode operate at higher heads and discharge as compared to the pump mode operation. BEP (best efficiency point) for the pump in hydro turbine mode is lower than in pump mode operation. Correlations proposed by earlier researchers for performance prediction of pump in hydro turbine mode are also tested.

Productivity enhancement and waste management through lean philosophy in Indian manufacturing industry

Value Stream Mapping has the reputation of uncovering waste in manufacturing, production and business processes by identifying and removing or streamlining value-added steps and eliminating non-value-added steps. The various process times for manufacturing a mono block pump were obtained from a pump manufacturing industry. A flow diagram showing the process is drawn to reflect the current state of the operation. The non-value actions are identified in each step and between each step by their waste of time and resources. The process is analyzed for opportunity to drastically reduce and simplify it to the fewest actions necessary. By reducing wastefulness the proportion of value adding time in the whole process rises and the process throughput speed is increased. This makes the redesigned process more effective (the right things are being done) and more efficient (needing fewer resources). The reengineered process is flow charted in its future state with process steps and information flows redesigned, simplified and made less expensive. This paper addresses the application of lean manufacturing concepts to the pump manufacturing industry.

Passive Strategy Based on Courtyard Building Morphology Impact on Thermal and Luminous Environments in Hot and Arid Region

The aim of the present research is to establish a dual relationship between thermal and the luminous environments of courtyard building in hot and arid regions. In hot and arid regions a design dilemma has always been problematic; lighting and protecting the building from insulation. To estimate the degree of correlation (thermal/luminous) which could be beneficial for designers, an on-site measurement campaign has been conducted in many old and new courtyard buildings with morphological variations, the software “DesignBuilder” has been used as the simulation tool, the simulations were under a clear sky condition in different seasons. The results are then to establish the optimal design solutions based on a special morphological analysis. The simulation testing with geometric modifications has proved essential in carrying out a comparative examination between the courtyard type and other Architectural form such as mono block type. The results show that courtyard building type performs well in terms of daylighting. However, it seems less efficient as thermal regulator. The comparative analysis determined the optimal architectural configuration in terms of building’s daylighting and thermal performances of in hot and arid regions.

First trial of SiC/SiC tube fabrication for tungsten monoblock armor

This article is reporting the practical steps of the first trial fabrication of SiC/SiC tube with tungsten mono block armor which it is applicable for fusion reactors actively cooling system, where the proceeding to fabricate actively cooling system during the fusion reaction is very important; to decrease the large amount of heat flux produced from neutron irradiation, so the FEEMA project inside Muroran institute of technology has taken an anticipated trial to fabricate this mock up to contribute actively towards the future fusion reactors. The facilities which have been used during the experimental work representing on the infiltration machines to produce both of prepreg sheets and preform by Nano-powder Infiltration and Transient Eutectoid (NITE) process, and warm isostatic press (WIP), as well as hot isostatic process (HIP). this works recorded the positives and drawback of the produced tube of SiC/SiC regarding to its durability, as well, its microstructure evolution. The optimum conditions of WIP for the SiC/SiC tube was the key element to produce high durable SiC/SiC tube in HIP stage. the results showed that; WIP conditions; of applied pressure; 6.5 Mpa, temperature 80 °C, and holding time 6 h, such conditions showed that the resulted SiC/SiC tube after HIP recorded maximum tensile strength up to 286 Mpa.

Physics conclusions in support of ITER W divertor monoblock shaping

The key remaining physics design issue for the ITER tungsten (W) divertor is the question of monoblock (MB) front surface shaping in the high heat flux target areas of the actively cooled targets. Engineering tolerance specifications impose a challenging maximum radial step between toroidally adjacent MBs of 0.3mm. Assuming optical projection of the parallel heat loads, magnetic shadowing of these edges is required if quasi-steady state melting is to be avoided under certain conditions during burning plasma operation and transiently during edge localized mode (ELM) or disruption induced power loading. An experiment on JET in 2013 designed to investigate the consequences of transient W edge melting on ITER, found significant deficits in the edge power loads expected on the basis of simple geometric arguments, throwing doubt on the understanding of edge loading at glancing field line angles. As a result, a coordinated multi-experiment and simulation effort was initiated via the International Tokamak Physics Activity (ITPA) and through ITER contracts, aimed at improving the physics basis supporting a MB shaping decision from the point of view both of edge power loading and melt dynamics. This paper reports on the outcome of this activity, concluding first that the geometrical approximation for leading edge power loading on radially misaligned poloidal leading edges is indeed valid. On this basis, the behaviour of shaped and unshaped monoblock surfaces under stationary and transient loads, with and without melting, is compared in order to examine the consequences of melting, or power overload in context of the benefit, or not, of shaping. The paper concludes that MB top surface shaping is recommended to shadow poloidal gap edges in the high heat flux areas of the ITER divertor targets.

An Experiment Study on Surface Roughness in High Speed Milling NAK80 Die Steel

The paper introduces that the high speed milling experiments on NAK80 die steel was carried out on the DMU 60 mono BLOCK five axis linkage high speed CNC machining center tool by the TiAlN coated tools, in order to research the effect of milling parameters on surface roughness R a . The results showed that the R a value increased with the decrease of milling speed v c , increased with the axial depth of milling a p , and feed per tooth f z and radial depth of milling a e . On the basis of the single factor experiment results, the mathematics model for between surface roughness and milling parameters were established by linear regression analysis.

Dimensional Accuracy Study of Open Cellular Structure CoCrMo Alloy Fabricated by Selective Laser Melting Process

Designing orthodontic implants with desired physical and biological performances and to fabricate net shape with complex anatomical shapes is still a challenge. Cautious design approaches followed by systematic manufacturing techniques that can achieve balanced physical performance in mono block implants mechanics is necessary to accomplish this objective. Metal additive manufacturing (MAM) technique such as selective laser melting (SLM) process is progressively being utilized for new biomaterials such as cobalt-chrome-molybdenum (CoCrMo). This study was designed to determine a dimensional accuracy of open cellular structures CoCrMo samples with designing volume based porosity ranging between 0 % (full dense) to 80 %. A maximum 2.10 % shrinkage was obtained by 80 % designed porosity sample. Samples with higher volume-to-surface area (full dense) demonstrated the low total amount of shrinkage as compared to lower volume-to-surface area (80 % designed porosity).

Modular titanium alloy neck failure in total hip replacement: analysis of a relapse case.

Modular neck hip prosthesis born in the 1990 with the aim of allowing the surgeon to modify CCD angle, offset and femoral anteversion intra-operatively restoring patient’s original biomechanics. In order to achieve the best biomechanics of the reconstructed hip, preoperative planning is essential. In the last few years modularity has been questioned and an argument made for the return to mono block stems due to events of breakage or disconnection of modular components. Fretting or crevice corrosion may lead to failure of such modular device due to the contamination inside the modular coupling or to high loads. We present a case of repetitive modular femoral neck prosthesis fracture.

Lead Time Reduction through Lean Technique in an Monoblock (SWJ1HP) Pump Industry

Value Stream Mapping has the reputation of uncovering waste in manufacturing, production and business processes by identifying and removing or streamlining value-added steps and eliminating non-value-added steps. The various process times for manufacturing a mono block pump were obtained from a pump manufacturing industry. The flow diagram showing the process is drawn to reflect the current state of the operation. The non-value actions are identified in each step and between each step by their waste of time and resources. The process is analyzed for opportunity to drastically reduce and simplify it to the fewest actions necessary. By reducing waste the proportion of value adding time in the whole process rises and the process throughput speed is increased. This makes the redesigned process more effective (the right things are being done) and more efficient (needing fewer resources). The reengineered process is flow charted in its future state with process steps and information flows redesigned, simplified and made less expensive. This paper addresses the application of lean manufacturing concepts to the pump manufacturing industry.

Effective Performance of an User Friendly Dynamic Tool Design in Small and Medium Scale Enterprises

This research addresses the implementations of agile philosophy in SME’s to increase the production flow rate. Every Small manufacturing industry has put in continuous efforts for its survival in the current volatile economy. In order to face the situation, industries are trying to implement new and efficient techniques in their manufacturing operations. In this research, a systematic approach of developing a user friendly dynamic tool for cycle time reduction and to improve the production flow rate. These effective tools mainly focus on reducing the non-value adding activities, queue time and delays. Here, we selected a medium scale pump industry for our research work and the various process times for manufacturing a mono block pump were obtained from a pump manufacturing industry. The result shows that the implementations of agile manufacturing concepts to the small scale pump manufacturing industry for increasing the production time and profit level.

Comparison of dimensionality reduction techniques for the fault diagnosis of mono block centrifugal pump using vibration signals

Bearing fault, Impeller fault, seal fault and cavitation are the main causes of breakdown in a mono block centrifugal pump and hence, the detection and diagnosis of these mechanical faults in a mono block centrifugal pump is very crucial for its reliable operation. Based on a continuous acquisition of signals with a data acquisition system, it is possible to classify the faults. This is achieved by the extraction of features from the measured data and employing data mining approaches to explore the structural information hidden in the signals acquired. In the present study, statistical features derived from the vibration data are used as the features. In order to increase the robustness of the classifier and to reduce the data processing load, dimensionality reduction is necessary. In this paper dimensionality reduction is performed using traditional dimensionality reduction techniques and nonlinear dimensionality reduction techniques. The effectiveness of each dimensionality reduction technique is also verified using visual analysis. The reduced feature set is then classified using a decision tree. The results obtained are compared with those generated by classifiers such as Naïve Bayes, Bayes Net and kNN. The effort is to bring out the better dimensionality reduction technique–classifier combination.

Fractured tooth rebonding: A ultra-conservative approach

Majority of the traumatic dental injuries involves the anterior teeth specially the maxillary incisors. Rebonding of the fractured fragment to the tooth retrieved in a fairly intact condition provides an ultra-conservative treatment option. Rebonding techniques provide good esthetics, restores immediate function and provides positive psychological support to the patient. With the introduction of resin based material and the mono block concept, rebonding is a feasible treatment procedure. These case reports discuss the techniques for rebonding fractured fragment to the tooth in a very conservative and cost-effective manner.Clinical Relevance to Interdisciplinary DentistryManagement of traumatic injuries requires a multidisciplinary approach.Fractured fragment rebonding where the fracture line violates the biological width will require periodontal procedures such as osteotomy, crown lengthening and gingivectomy to be carried out.With the advancement in materials and techniques fractured fragment rebonding offers a viable restorative option for the clinician which restores immediate esthetics using an ultra-conservative approach.