Research on calculation of grinding surface roughness

In machining processes, grinding is often chosen as the final machining method. Grinding is often chosen as the final machining method. This process has many advantages such as high precision and low surface roughness. It depends on many parameters including grinding parameters, dressing parameters and lubrication conditions. In grinding, the surface roughness of a workpiece has a significant influence on quality of the part. This paper presents a study of the grinding surface roughness predictions of workpieces. Based on the previous studies, the study built a relationship between the abrasive grain tip radius and the Standard marking systems of the grinding wheel for conventional and superabrasive grinding wheels (diamond and CBN abrasive). Based on this, the grinding surface roughness was predicted. The proposed model was verified by comparing the predicted and experimental results. Appling the research results, the surface roughness when grinding three types of steel D3, A295M and SAE 420 with Al2O3 and CBN grinding wheels were predicted. The predicted surface roughness values were close to the experimental values, the average deviation between predictive results and experimental results is 15.11 % for the use of Al2O3 grinding wheels and 24.29 % for the case of using CBN grinding wheels. The results of the comparison between the predicted model and the experiment show that the method of surface roughness presented in this study can be used to predict surface roughness in each specific case. The proposed model was verified by comparing the predicted and measured results of surface hardness. This model can be used to predict the surface hardness when surface grinding

Dose Distribution of 192Ir HDR Brachytherapy Source Measurement using Gafchromic® EBT3 Film Dosimeter and TLD-100H

This study aims to measure the radial dose function and anisotropy function F(r, θ) of high Dose Rate (HDR) 192Ir source in a fabricated water-equivalent phantom using Gafchromic® EBT3 film and TLD-100H and to compare the results obtained with the MCNP5 calculated values. The phantom was fabricated using Perspex PMMA material. For, the EBT3 films with a required dimension and TLD-100H chips were placed at r=1, 2, 3, 5, and 10 cm from the source. The F(r, θ) measurements were carried out at r=1, 2, 3, 5, and 10 cm with the angle range from 10° to 170°. The result of from EBT3 film and TLD-100H was in good agreement (2.10%±1.99). Compared to MCNP5, the differences are within 0.31% to 11.47% for EBT3 film and 0.08% to 10.58% for TLD-100H. For the F(r, θ), an average deviation with the MCNP5 calculation is 4.94%±2.7. For both and F(r, θ), the effects are prominent at r=10 cm. At this distance, the response of both Gafchromic® EBT3 film and TLD-100H shows less sensitivity as the dose followed the inverse square law. This work demonstrates that Gafchromic® EBT3 film dosimeter and TLD-100H are suitable dosimeters in 192Ir dosimetric measurements at a radial distance of ˂5 cm

A Comparative Study on a Novel Fibula Malleolus Cap to Increase the Accuracy of Oncologic Jaw Reconstruction

ObjectivesAlthough computer-assisted surgery using fibula flap has been widely applied for oncologic jaw reconstruction in recent years, the inaccurate positioning of the fibula harvest guide brings sliding and rotational errors, which leads to compromised accuracy in simultaneous implant placement and dental rehabilitation. This study aimed to develop a novel three-dimensional (3D)-printed patient-specific fibula malleolus cap to increase oncologic reconstruction accuracy.MethodsIn this prospective comparative study with a recent historical control cohort, patients in need of oncologic jaw reconstruction with fibula free flaps were recruited. In the study group, the fibula was harvested with the guide of the malleolus cap, whereas in the control group, without the malleolus cap. Deviations of location and angulation of distal fibula osteotomies, jaw reconstruction segments, and simultaneous dental implants were compared.ResultsTwenty patients were recruited, with 10 in each arm. The application of the malleolus cap significantly reduced the deviations in locations and angles of distal fibula osteotomies, from 9.5 to 4.1 mm and 25.3° to 8.7°. For the simultaneous dental implants placed in the fibula flaps, there was a significant increase in the accuracy of implant platform locations (the average deviation from 3.2 to 1.3 mm), apex locations (from 3.8 to 1.5 mm), and angles (from 11.3° to 4.6°). No significant difference was detected in the accuracy of fibula reconstruction segments.ConclusionsWe developed a novel fibula malleolus cap to overcome the sliding and rotational errors during fibula flap harvesting for oncologic jaw reconstruction, with increased accuracy in simultaneous dental implants. This is a step forward to achieve a satisfactory functional outcome of jaw reconstruction with dental rehabilitation.

Determination of Dimethylamine Content in Dimethylhydrazine Based on Partial Least Squares Method

Based on partial least squares, the dimethyl monomethyme content was measured. The original spectroscopy, smooth, first-order differential, second-order differential, multi-scattered correction, standard regular conversion, the main cause of the child were effectively used. The results show that the model performance of 6 main factors established separately, the correction set coefficient and verification set coefficient of correction set is 0.9999 and 0.9991, respectively, and the correlation set prediction standard deviation is 0.00356, respectively. And 0.0178. This optimal model is used to measure the blind sample of modeling. As a result, the deviation of the measurement results is between -0.028% ∼ 0.012%, the average deviation is from 0.014%, the standard deviation is 0.014%, and the relative standard deviation is 2.9%. The result is satisfactory.

3 kW Thermoelectric Generator for Natural Gas-Powered Heavy-Duty Vehicles—Holistic Development, Optimization and Validation

Emissions from heavy-duty vehicles need to be reduced to decrease their impact on the climate and to meet future regulatory requirements. The use of a cost-optimized thermoelectric generator based on total cost of ownership is proposed for this vehicle class with natural gas engines. A holistic model environment is presented that includes all vehicle interactions. Simultaneous optimization of the heat exchanger and thermoelectric modules is required to enable high system efficiency. A generator design combining high electrical power (peak power of about 3000 W) with low negative effects was selected as a result. Numerical CFD and segmented high-temperature thermoelectric modules are used. For the first time, the possibility of an economical use of the system in the amortization period of significantly less than 2 years is available, with a fuel reduction in a conventional vehicle topology of already up to 2.8%. A significant improvement in technology maturity was achieved, and the power density of the system was significantly improved to 298 W/kg and 568 W/dm3 compared to the state of the art. A functional model successfully validated the simulation results with an average deviation of less than 6%. An electrical output power of up to 2700 W was measured.

Development of an Approach for Determining the Effectiveness of Inhibition of Paraffin Deposition on the Wax Flow Loop Laboratory Installation

The formation of wax deposits is a common phenomenon in the production and transportation of formation fluids. On the territory of the Perm Krai, this problem occurs in half of the mining funds. One of the most common and promising methods of dealing with these deposits is the use of inhibitor regents. The most popular technique for assessing the effectiveness of a wax inhibitor is the «Cold Finger», which has a number of significant drawbacks. This work presents a number of methods for assessing the effectiveness of inhibition of paraffin formation on the laboratory installation «WaxFlowLoop». A number of laboratory studies have been carried out to determine the effectiveness of a paraffin deposition inhibitor for inhibiting the paraffin formation process of four target fluids. Verification of the obtained values was carried out by comparing them with the field data. As a result of laboratory studies, it was found that the value of the inhibitor efficiency, determined by the «Cold Finger» method, differs from the field data by an average of 2 times. At the same time, the average deviation of the results determined at the «WaxFlowLoop» installation from the field data is 8.1%. The correct selection of a paraffin deposition inhibitor and its dosage can significantly increase the inter-treatment period of the well, thereby reducing its maintenance costs and increasing the efficiency of well operation.

Assessment of Remote Sensing Techniques Applicability for Beach Morphology Mapping: A Case Study of Hvar Island, Central Adriatic, Croatia

This study investigates the quality and accuracy of remote sensing data in beach surveys based on three different data sources covering a 10-year period (2011–2021). Orthophotos from State Geodetic Administration Geoportal and satellite imagery from Google Earth were compared with orthophotos generated from UAV using ArcGIS Pro and Drone2Map. The beach area and length of 20 beaches on the island of Hvar were measured using each data source from different years. The average deviation for beach area (−2.3 to 5.6%) and length (−1 to 2.7%) was determined (without outliers). This study confirms that linear feature measurement is more accurate than polygon-based measurement. Hence, smaller beach areas were associated with higher errors. Furthermore, it was observed that morphological complexity of the beach may also affect the measurement accuracy. This work showed that different remote sensing sources could be used for relatively accurate beach surveys, as there is no statistically significant difference between the calculated errors. However, special care should always be addressed to the definition of errors.

Analysis and Calculation of Stability Coefficients of Cross-Laminated Timber Axial Compression Member

Cross-laminated timber (CLT) elements are becoming increasingly popular in multi-storey timber-based structures, which have long been built in many different countries. Various challenges are connected with constructions of this type. One such challenge is that of stabilizing the structure against vertical loads. However, the calculations of the stability bearing capacity of the CLT members in axial compression in the structural design remains unsolved in China. This study aims to determine the stability bearing capacity of the CLT members in axial compression and to propose the calculation method of the stability coefficient. First, the stability coefficient calculation theories in different national standards were analyzed, and then the stability bearing capacity of CLT elements with four slenderness ratios was investigated. Finally, based on the stability coefficient calculation formulae in the GB 50005-2017 standard and the regression method, the calculation method of the stability coefficient for CLT elements was proposed, and the values of the material parameters were determined. The result shows that the average deviation between fitting curve and calculated results of European and American standard is 5.43% and 3.73%, respectively, and the average deviation between the fitting curve and the actual test results was 8.15%. The stability coefficients calculation formulae could be used to predict the stability coefficients of CLT specimens with different slenderness ratios well.

Embedded acoustic long baseline localization system for autonomous underwater vehicles

<p>The attenuation of global positioning system (GPS) in water medium makes localization of autonomous uderwater vehicles (AUVs) particularly challenging. The long baseline (LBL) positioning system can extend GPS using beacons as references. This work aims at building an acoustic LBL-based system able to localize AUVs operating in swarms thanks to a small size acoustic transceiver embedded onboard AUVs and implementing range-based localization algorithms to estimate the swarm coordinates in real-time. The distances computation between navigating AUVs and fixed beacons were implemented in a digital signal processor (DSP) which computes the time-of-arrival (ToA) of incoming pure tone acoustic waves. The principle of design, hardware architecture, implementation, simulations and sea experiments are described in this paper. The experimental data showed an average deviation around 0.62 m when an AUV is placed at 45 m far away from a beacon. This deviation increases with distance: around 4.8 m measured at 500 m. This performance can be improved by taking into consideration the two main factors examined in this paper, which are sound velocity profile and propagation model.</p>

Enhancing septoria leaf blotch forecasts in winter wheat II: model architecture and validation results

In precision agriculture, pesticides and other inputs shall be used precisely when (and where) they are needed. European Directive 2009/128/EC calls for respecting the principles of integrated pest management (IPM) in the member states. To clarify the question, when, for instance, fungicide use is needed, the well-established economic principle of IPM may be used. This principle says that pests shall be controlled when the costs of control correspond with the damage the pests will cause. Disease levels corresponding with the costs of control are referred to as control thresholds in IPM. Several models have been developed in plant pathology to predict when epidemics will occur, but hardly any of these models predicts a control threshold directly limiting their usefulness for answering the question when pest control is needed according to the principles of IPM. Previously, we quantified the temporal distance between critical rainfall periods and the breaking of the control threshold of Zymoseptoria tritici on winter wheat as being affected by temperature, based on data from 52 field experiments carried out in Luxembourg from 2005 to 2016. This knowledge was used to construct the ShIFT (SeptorIa ForecasT, https://shift.list.lu/) model, which has been validated using external data recorded between 2017 and 2019. Within the efficacy period of a systemic fungicide, the model allowed correct predictions in 84.6% of the cases, while 15.4% of the cases were predicted falsely. The average deviation between the observed and predicted dates of epidemic outbreaks was 0.62 ± 2.4 days with a maximum deviation of 19 days. The observed and predicted dates were closely correlated (r = 0.92, P < 0.0001). Apart from outliers, the forecast model tested here was reliable within the period of efficacy of current commercial fungicides.