Travel Angle Research Articles

Design of a precise subdivision system for gratings using a modified CORDIC algorithm

The authors have proposed a robust linearisation method for determining the angles of sinusoidal signals generated by gratings. This scheme solves the problem of non-linear subdivision by compensating sinusoidal signal. The conventional coordinate rotation digital computer (CORDIC) algorithm is optimised by double-rotation iteration, and the calculation accuracy of arcsine and arccosine functions is improved. A pipeline preprocessing circuit based on the CORDIC is designed for the signal compensation and digital subdivision. The two processes are implemented on a field-programmable gate array chip, which exhibits a wide input range and good dynamic response. A theoretical analysis using stable signals from a function generator verifies that the subdivision system achieves the ideal subdivision effect. The subdivision system is further applied to an angle-measuring device for a 16,384-line circular grating. The results of subdivision exhibit good linearity for the grating moire signal. Compared to the angular measurement by a laser interferometer within the three grating lines, the angle-measurement accuracy of ±0.000138° (0.5″) and the relative error is ±0.63% over a travel angle of three grating lines. Notably, the measurement error of the subdivision system is only half of that in a similar commercial product (MicroE system).

A probabilistic model of weld penetration depth based on process parameters

In welded structures using robotized metal active gas (MAG) welding, unwanted variation in penetration depth is typically observed. This is due to uncertainties in the process parameters which cannot be fully controlled. In this work, an analytical probabilistic model is developed to predict the probability of satisfying a target penetration, in the presence of these uncertainties. The proposed probabilistic model incorporates both aleatory process parameter uncertainties and epistemic measurement uncertainties. The latter is evaluated using a novel digital tool for weld penetration measurement. The applicability of the model is demonstrated on fillet welds based on an experimental investigation. The studied input process parameters are voltage, current, travel speed, and torch travel angle. The uncertainties in these parameters are modelled using adequate probability distributions and a statistical correlation based on the volt-ampere characteristic of the power source. Using the proposed probabilistic model, it is shown that a traditional deterministic approach in setting the input process parameters typically results in only a 50% probability of satisfying a target penetration level. It is also shown that, using the proposed expressions, process parameter set-ups satisfying a desired probability level can be simply identified. Furthermore, the contribution of the input uncertainties to the variation of weld penetration is quantified. This work paves the way to make effective use of the robotic welding, by targeting a specified probability of satisfying a desired weld penetration depth as well as predicting its variation.

Comparative analysis of cylindrical thread and straight square profile pin on ultimate tensile strength of AA8011/AZ31B in friction stir butt welding

Abstract Prediction and comparative analysis of ultimate tensile strength in friction stir butt welding of Aluminium alloy-AA8011 and Magnesium alloy-AZ31B using different tool rotational speed, tool travel feed and tool tilt angle for cylindrical thread and straight square profile pin are presented in this work. The methodology is based on Taguchi method and the regression analysis. In this comparative experimental study, the purpose is to establish a correlation between the tool rotational speed, tool travel speed and tool tilt angle with the induced ultimate tensile strength in the weld for cylindrical thread and straight square profile pin. Analysis of variance is employed to find influence factor. The best tool is identified based on ultimate tensile strength value and also prediction is carried out for best tool profile pin. From this comparative analysis found that tool rotational speed is most important factor for cylindrical thread and straight square profile pin.

Semi-quantitative method to identify the vulnerable areas in terms of building aggregation for probable landslide runout at the regional scale: a case study from Soacha Province, Colombia

Landslide susceptibility and vulnerability maps are key components for urban planning and risk management. The main objective of this research was spatial vulnerability mapping in the probable landslide runout zone in Soacha Province, Colombia. This study included three major steps: identification of a landslide susceptible area, identification of its runout zone, and vulnerability assessment using an area damage index method. The landslide-prone area was identified through a susceptibility analysis using a logistic regression model. In total, 182 landslide locations were collected and randomly distributed as training data (70%) and validation data (30%). The final landslide susceptibility map was validated using the area under the curve method. The validation result showed success and prediction rates of 88.71% and 89.96%, respectively. The Flow-R model was applied to identify the runout zone, and a back-propagation analysis approach was applied to estimate two essential input data for the model, i.e., the travel angle and velocity. From seven locations, the back-propagation analysis showed an average travel angle of 14.6° and an average velocity of 11.4 m/s. A total of 3777 buildings were identified within the probable runout zone. A physical vulnerability assessment was done by finding the ratio between area of buildings and area of runout zone in each small unit boundary. The physical vulnerability was classified as low, moderate, extensive, and complete on the basis of building exposure. The final result revealed that most of the village areas are in null or moderate vulnerability zones. In contrast to the village areas, the city areas include zones of extensive and complete vulnerability. This study showed that about 52% of the area of the city of Cazuca is completely vulnerable, i.e., in areas where abandoned quarry sites are present. The map of vulnerable areas may assist planners in overall landslide risk management.

Suppressing the Noise in Measured Signals for the Control of Helicopters

This paper concerns with the non-linear system having multiple-inputs multiple-outputs (MIMO). The plant mainly comprises: bench-top helicopter, tail and main rotor of a helicopter system. The dynamics are presented with control methodologies where a conventional strategy proves the instability of the system while the deadbeat and sliding mode control with linear matrix inequality regulates the future estimates. There have been disturbances like presence of unwanted ripples in the output of the non-linear systems (in case of stability also after 100[Formula: see text]s) and in the tracking of states accurately by updating the minimization error regularly. These problems originate mainly from the rotor section and are visited carefully by studying the dynamics of the blade, whereas, the design of filter makes the solution more appealing. The adaptive filter is capable of handling the frequency spectra of noise (reducing noise by 10[Formula: see text]dB), Euler angle deviations and travel angle accurately. Also, the stability analysis does not confirm the behavior in the case of bounded and a varying range of initial angular velocity. Hence, the problem of fluctuations is overcome by deadbeat and SMC-LMI approach which not only improved the ripples but also allowed the final response of the future states to be more exact and noiseless. As the previous research involved in position tracking (either translational or rotational) of these MIMO systems was concerned with software tools like MATLAB. This paper justifies its validation tested experimentally on OPAL RT hardware. The key findings involve the comparison of frequency spectra, the Euler deviation plot compared to CSL Helicopter and the three set-point variations providing accuracy in results in four modes — desired, actual, with controller-without filter and with controller-with filter. The use of adaptive filter with controllers have encouraged the suppression of noisy waveforms in the bench-top system very smoothly. The details regarding hardware setup are also discussed.

Analysis of Landslide Vulnerabilities in Small and Medium-Sized Cities of ColombiaⅠ: With Focus on Physical Vulnerability

Colombia has experienced many problems in its urban areas due to increase in population in these areas. In particular, because of recurring slope disasters in urban areas, it has become necessary for the Colombian government to analyze these hazards. In this study, we selected a test bed with a high-potential source area in the small and medium city and conducted the physical vulnerability assessment of the test bed. First, we collected and analyzed the causal factors and landslide inventory. Using the landslide inventory and spatial information database, we performed a susceptibility assessment to identify high-potential landslide source areas. Next, we defined the parameters (travel angle, maximum velocity, etc.) for the Flow-R model analysis, which we used to calculate the propagation zone of debris flow. For the vulnerability assessment, we used road sections to define the boundary zones. Finally, we developed and evaluated the physical vulnerability map of Soacha using the propagation zones of debris flow and the boundary zones. The physical vulnerability assessment technique developed through this study will provide useful information for future urban planning and disaster prevention in Colombia. Keywords: Landslide, Physical Vulnerability, Spatial Information, Flow Analysis

Effects of welding current and torch position parameters on bead geometry in cold metal transfer welding

This study investigated the effects of welding current and torch position parameters, including torch-aiming position, travel angle, and work angle, on bead geometry in single-lap joint gas metal arc (GMA) welding. High-speed filming and macrographs of weld cross section were used to observe the effect of each welding parameter on the properties of the bead geometry, including penetration, leg length, and toe angle. Response surface methodology was used to establish the relationship between the welding parameters and properties of bead geometry and to estimate regression models for predicting bead geometry. Both welding current and torch-aiming position were found to have significant effects on bead geometry, with strong linearity between them and bead geometry. The coefficient of determination (R2) of the estimated response surface models was 0.7226 for penetration, 0.8802 for leg length, and 0.8706 for toe angle. Further, experimental results indicate that the estimated models are very effective.

Effects of volume and topographic parameters on rockfall travel distance: a case study from NW Himalayas, Pakistan

This paper presents an analysis of rockfall travel distance for incidents along the roads of the Abbottabad and Mansehra Districts, Khyber Pakhtunkhwa, Pakistan. Data for 121 rockfall events ranging from 100 m 3 to 10 000 m 3 volume were gathered during field investigations and used to facilitate an assessment of parameters such as height of fall, travel angle, travel distance and rockfall volume. The relationship between the height of fall and travel distance was investigated using well-established empirical approaches published in the literature. This analysis showed that travel angle decreased with increase in the rockfall volume, but that there was a weak correlation between the volume of rockfall and travel distance. A strong positive relationship between the travel distance and the height of fall was also identified. Comparison of the rockfall events identified during this study and existing data published from other regions in the world shows that the characteristics of the rockfalls are largely consistent with those identified by previous investigations. The study findings provide a useful set of data for empirical analyses that may be used for hazard and risk assessment in the region.

Debris flow susceptibility assessment based on an empirical approach in the central region of South Korea

Many debris flow spreading analyses have been conducted during recent decades to prevent damage from debris flows. An empirical approach that has been used in various studies on debris flow spreading has advantages such as simple data acquisition and good applicability for large areas. In this study, a GIS-based empirical model that was developed at the University of Lausanne (Switzerland) is used to assess the debris flow susceptibility. Study sites are classified based on the types of soil texture or geological conditions, which can indirectly consider geotechnical or rheological properties, to supplement the weaknesses of Flow-R which neglects local controlling factors. The mean travel angle for each classification is calculated from a debris flow inventory map. The debris flow susceptibility is assessed based on changes in the flow-direction algorithm, an inertial function with a 5-m DEM resolution. A simplified friction-limited model was applied to the runout distance analysis by using the appropriate travel angle for the corresponding classification with a velocity limit of 28 m/s. The most appropriate algorithm combinations that derived the highest average of efficiency and sensitivity for each classification are finally determined by applying a confusion matrix with the efficiency and the sensitivity to the results of the susceptibility assessment. The proposed schemes can be useful for debris flow susceptibility assessment in both the study area and the central region of Korea, which has similar environmental factors such as geological conditions, topography and rainfall characteristics to the study area.

Effects of welding current and torch position parameters on minimizing the weld porosity of zinc-coated steel

This study involves an investigation of the effects of the welding current and torch position parameters, including the travel angle, torch-aiming position, and work angle, on reducing the weld porosity in the cold metal transfer (CMT) welding of hot-dip galvannealed steel in the lap-joint configuration. The effects of the welding parameters on the weld porosity are investigated through statistical analysis, high-speed imaging of the weld pool behavior, welding signal analysis, and scanning electron microscopy (SEM) analysis. The magnitude of the welding current influences the weld porosity and weld pool behavior because the current determines the arc force, the heat input, the amount of zinc vaporization, and the weld pool viscosity. The torch position parameters also have considerable effects on the weld porosity because they determine where the arc, arc force, and heat input are concentrated. A response surface model relating the welding parameters and the amount of weld porosity is estimated, and the optimum welding conditions and a suitable welding range are determined on the basis of the estimated model to minimize the weld porosity in the CMT welding of hot-dip galvannealed steel.

Study on weld seam surface deposits of CuSi3 CMT brazing

CuSi3 CMT brazing is an advanced welding technology widely used in automotive industry. But dark deposits defect was found on the weld seam surface. SEM and EDS analyses were operated in this paper and this surface was found to contain three areas: area A with silicates thin film and Cu, area B with MnO·SiO2 silicates, and area C with CuO. And thus the formation mechanism of surface deposits, which was mainly attributed to the generation and uneven distribution of large amount of dark CuO, was proposed. Based on the mechanism of the deposit formation, four methods were processed to suppress the surface dark deposits. Ar + 2%O2 would prevent the generation of dark deposits because of enhanced cathode crushing effect. Besides, delay gas protection time, keep torch travel angle positive, and maintain a low heat input would be benefit for suppressing dark deposits on the weld seam surface.

Interval Type-2 Fuzzy Sliding Mode Controller Based on Nonlinear Observer for a 3-DOF Helicopter with Uncertainties

In this paper, a robust controller for a three degree of freedom helicopter control is proposed in presence of modeling error and disturbance. In this frame, interval type-2 fuzzy logic control approach (IT2FLC) and sliding mode control (SMC) techniques are used to design a controller named interval type-2 fuzzy sliding mode controller (IT2FSMC). Elevation, pitch and travel angles are considered measurable, whereas unmeasured states are estimated by using a nonlinear observer. The proposed control scheme can not only attenuate the chattering effect of the SMC, but also it reduces the rules number of the fuzzy controller. As for stability, it is exponentially guaranteed by using the Lyapunov criteria. The simulation results show that the IT2FSMC significantly alleviates the chattering effect and provides a good tracking performance, in the presence of modeling error and disturbance. They also illustrate that the IT2FSMC achieves the best tracking performance in comparison with the type-1 fuzzy logic controller, the IT2FLC and the type-1 fuzzy sliding mode controller.

Experimental Study on the Mobility of Channelized Granular Mass Flow

AbstractGranular mass flows (e.g., debris flows/avalanches) in landslide‐prone areas are of great concern because they often cause catastrophic disasters as a result of their long run‐out distances and large impact forces. To investigate the factors influencing granular mass flow mobility, experimental tests were conducted in a flume model. Granular materials consisting of homogeneous sand and non‐homogeneous sandy soil were used for studying particle size effects. Run‐out tests with variable flow masses, water contents, and sloping channel confinement parameters were conducted as well. The results indicated that granular mass flow mobility was significantly influenced by the initial water content; a critical water content corresponding to the smallest flow mobility exists for different granular materials. An increase in the total flow mass generally induced a reduction in the travel angle (an increase in flow mobility). Consistent with field observations, the travel angles for different granular materials decreased roughly in proportion to the logarithm of mass. The flume model tests illustrate that the measured travel angles increase as the proportion of fine particles increases. Interestingly, natural terrain possesses critical confinement characteristics for different granular mass flows.

Monitoring and early warning of the 2012 Preonzo catastrophic rockslope failure

In this paper, we describe the investigations and actions taken to reduce risk and prevent casualties from a catastrophic 210,000 m3 rockslope failure, which occurred near the village of Preonzo in the Swiss Alps on May 15, 2012. We describe the geological predisposition and displacement history before and during the accelerated creep stage as well as the development and operation of an efficient early warning system. The failure of May 15, 2012, occurred from a large and retrogressive instability in gneisses and amphibolites with a total volume of about 350,000 m3, which formed an alpine meadow 1250 m above the valley floor. About 140,000 m3 of unstable rock mass remained in place and might collapse partially or completely in the future. The instability showed clearly visible signs of movements along a tension crack since 1989 and accelerated creep with significant hydromechanical forcing since about 2006. Because the active rockslide at Preonzo threatened a large industrial facility and important transport routes located directly at the toe of the slope, an early warning system was installed in 2010. The thresholds for prealarm, general public alarm, and evacuation were derived from crack meter and total station monitoring data covering a period of about 10 years, supplemented with information from past failure events with similar predisposition. These thresholds were successfully applied to evacuate the industrial facility and to close important roads a few days before the catastrophic slope failure of May 15, 2012. The rock slope failure occurred in two events, exposing a compound rupture plane dipping 42° and generating deposits in the midslope portion with a travel angle of 39°. Three hours after the second rockslide, the fresh deposits became reactivated in a devastating debris avalanche that reached the foot of the slope but did not destroy any infrastructure. The final run-out distance of this combined rock collapse–debris avalanche corresponded to the predictions made in the year 2004.

Travel Angle Control of Quanser Bench-top Helicopter based on Quantitative Feedback Theory Technique

<p>A three degree of freedom (3-DOF) bench-top helicopter is a simplified aerial vehicle which is used to study the behaviors of the helicopter as well as testing multiple flight control approaches for their efficiency. Designing helicopter’s dynamic control is a challenging task due to the presence of high uncertainties and non-linear behavior. The main objective of this research is to achieve robust control over the helicopter model regardless parameter variation and disturbances using robust control technique, Quantitative Feedback Theory (QFT). QFT utilizes frequency domain methodology which ensures plant’s stability by considering the feedback of the system and thus removing the effect of disturbances and reducing sensitivity of parameter’s variation. The proposed technique is tested against LQR-tuned PID controller in both simulation and real hardware environment to verify its performance. The results obtained shown us that QFT algorithm managed to reduce settling time and steady state error of about 80% and 33% respectively over the classical PID controller.</p>

Deep Research on the High Speed Printing Machine Mechanism Output Member

This article is an expand research about second size synthesis task of disc mechanism with floating roller push rod. By taking the cam-linkage combination mechanism of high speed printing machine as the research object, the travel angle of rocker m of its output member was analyzed and explored. According, in different allowable pressure angles [], relationship of zC, r0 and m were analyzed, optimal pressure angle []* and optimal cam basic radius r0opt * were solved. Regardless of digging the potential of existing mechanisms or extending scalable coverage, the above analyses have important reference value and guiding significance.

Effect of torch position and angle on welding quality and welding process stability in Pulse on Pulse MIG welding–brazing of aluminum alloy to stainless steel

In this paper, Pulse on Pulse metal inert gas (MIG) welding–brazing of 6061 aluminum alloy to 304 stainless steel in a lap configuration was developed to investigate the effect of torch position and angle on the welding quality and welding process stability. Images of arc, electrical signals of welding current, and welding voltage were acquired in synchronous modes by a high-speed camera and electrical signal acquisition system, respectively. The obtained results demonstrate that arc shape, macrostructure, microstructure, and mechanical properties are sensitive to torch aiming position when torch travel angle is 20° and work angle is 0°. However, when travel angle is 20° and work angle is 20°, the effect of torch aiming position is insignificant. It is easier to strike arc and maintain it on the surface of aluminum alloy compared to stainless steel. High-strength joints, whose fracture occurred at heat-affected zones of Al alloys at 89 MPa up to 72 % of the tensile strength of Al alloys, have been obtained. Moreover, a comprehensive evaluation method for the welding process stability based on statistical techniques has been proposed. This method can be easily and quickly integrated in real-time control of the welding process, which provides a quantitative guidance in MIG welding–brazing of aluminum alloy to stainless steel.

Optimization and Prediction of Ultimate Tensile Strength in Metal Active Gas Welding.

We investigated the effect of welding parameters on ultimate tensile strength of structural steel, ST37-2, welded by Metal Active Gas welding. A fractional factorial design was used for determining the significance of six parameters: wire feed rate, welding voltage, welding speed, travel angle, tip-to-work distance, and shielded gas flow rate. A regression model to predict ultimate tensile strength was developed. Finally, we verified optimization of the process parameters experimentally. We achieved an optimum tensile strength (558 MPa) and wire feed rate, 19 m/min, had the greatest effect, followed by tip-to-work distance, 7 mm, welding speed, 200 mm/min, welding voltage, 30 V, and travel angle, 60°. Shield gas flow rate, 10 L/min, was slightly better but had little effect in the 10–20 L/min range. Tests showed that our regression model was able to predict the ultimate tensile strength within 4%.

Angular Stability Margins for the Remote Fusion Cutting Process

The set of incident angles, that yields stable cuts when conducting remote fusion cutting (RFC), is of great importance when scheduling multiple cuts on a work piece. This is due to their ability to determine how much the laser beam can be moved by angling the cutting head instead of translating it. This paper investigates how the stability of the RFC process is affected by changing the incident angle when processing stainless steel sheets. This investigation was conducted as an experimental study in which the angle of incidence was decomposed into a work angle and a travel angle. The stability was evaluated by an automatic procedure based on images acquired by a programmable microscope and a computer vision algorithm developed in MATLAB. The results showed that the stability of the RFC process was dependent on the work and the travel angle. It was also seen that a coherent region of stable incident angles could be found. All experiments were conducted with a 3kW single mode fiber laser at the laser processing laboratory at Aalborg University.

Optimization of degree of sphericity of primary phase during cooling slope casting of A356 Al alloy: Taguchi method and regression analysis

The present work presents the results of experimental investigation of semi-solid rheocasting of A356 Al alloy using a cooling slope. The experiments have been carried out following Taguchi method of parameter design (orthogonal array of L9 experiments). Four key process variables (slope angle, pouring temperature, wall temperature, and length of travel of the melt) at three different levels have been considered for the present experimentation. Regression analysis and analysis of variance (ANOVA) has also been performed to develop a mathematical model for degree of sphericity evolution of primary α-Al phase and to find the significance and percentage contribution of each process variable towards the final outcome of degree of sphericity, respectively. The best processing condition has been identified for optimum degree of sphericity (0.83) as A3, B3, C2, D1 i.e., slope angle of 60°, pouring temperature of 650°C, wall temperature 60°C, and 500mm length of travel of the melt, based on mean response and signal to noise ratio (SNR). ANOVA results shows that the length of travel has maximum impact on degree of sphericity evolution. The predicted sphericity obtained from the developed regression model and the values obtained experimentally are found to be in good agreement with each other. The sphericity values obtained from confirmation experiment, performed at 95% confidence level, ensures that the optimum result is correct and also the confirmation experiment values are within permissible limits.