On the use of areal roughness parameters to assess surface quality in laser cutting of stainless steel with CO2 and fiber sources

"Laser cutting provides various advantages such as high flexibility in terms of process parameters and cut material type, as well as the possibility to obtain complex geometry in different dimensions with high precision. From industrial point of view, the two more competitive laser cutting technologies are based on the use of CO2 and active fiber sources, which produce samples visually different, with non-uniform surface and different depth of the striations. The quality assessment between the two laser systems within the industry is commonly based on standard ISO 9013; that covers several aspects of quality, the most used are the surface roughness and edge perpendicularity; however 2D profilometers adopted for measures are not able to analyze the complex 3D surface topography of the cutting edge. As a result, despite the fact that the differences are visually appreciated, measured 2D roughness values of different CO2 and fiber laser cutting conditions are very similar. Recently, a greater diffusion of 3D surface profilometry devices is present. These devices allow areal surface roughness parameters to be defined, which are potentially suitable to better quantify the laser cut quality. This work points out the use of a focus-variation microscopy to acquire 3D surfaces and evaluate analytically the surface quality of laser cut edges using areal surface roughness parameters. In particular, the purpose is to define a simple and repeatable method to identify the type of cutting process analyzed through the reconstruction of surface characteristics and quality of the cut-edge. As a case study, two stainless steel samples with the same geometry obtained with different laser sources, CO2 and active, fiber is presented. For comparison purposes the cutting conditions were fixed to represent the state of the art of respective laser cutting technologies, which actually show distinct cutting edge characteristics.

Enhanced Gas Recovery with Carbon Dioxide Sequestration in a Water-drive Gas Condensate Reservoir: a Case Study in a Real Gas Field

Gas reservoirs usually have high recovery due to high mobility and low residual gas saturation, although some of them producing under water-drive mechanism have low recovery efficiency. Encroachment of water into these reservoirs traps considerable amount of gas and increases the maximum residual gas saturation, which results in the reduction of gas and condensate production. Generally, the recoveries of water-drive gas reservoirs vary between 35-75%, whereas depletion-drive reservoirs exhibit recoveries near 85%. In this work, a method was proposed for reducing water encroachment, sweeping reservoir gas content effectively, and enhancing the hydrocarbon recovery consequently. To this end, a condensate gas reservoir model, located in the south of Iran, was chosen to study the process. The injection was performed above the bottom-up aquifer from two horizontal wells, and the base gas was produced by four vertical wells. Three cases of inactive aquifer (Case I), active aquifer (Case II), and active aquifer with CO2 injection (Case III) were studied subsequently. The proposed gas-gas displacement method increases the recovery of reservoir especially the recovery of heavier components composing the main part of the condensate. Moreover, the injection of a huge volume of CO2 without significant CO2 production can be interesting from an environmental point of view and can be considered as a CO2 sequestration process

Steer-by-switch system design for vehicles

In this paper, design of a steer-by-switch system as a new technology to steer vehicles devoid of a steering wheel was described. In this method, steering of the vehicle was achieved by two push button switches which were related to the front wheels via an electro-hydro-mechanical system. The objective of this design was to eliminate the prejudicial effects associated with the utilisation of steering wheels in machines. Furthermore, this system provided a flexible and comfortable steering for drivers of heavy duty machinery and off-road vehicles as well as the feasibility of driving for invalid persons who were feeble in one hand. Modeling of the system was achieved to compare its characteristics with two common types of steering systems. To enhance the reliability of the system, an auxiliary steering system served as a safeguard against the failure of the main steering system

Coordination of recognition and disclosure decisions in uncertainties reporting: investigating the relationship between conditional conservatism and risk disclosu

Accounting Conservatism and risk disclosure are two information policies that managers can use to transfer business uncertainties to external users. Managers are expected to coordinate their reporting and disclosure choices by considering the cost and benefit of these two choices when making financial reporting decisions and coordinate or trade off the two options of conservatism and risk disclosure. This study investigated the relationship between conditional conservatism and risk disclosure. It also analyzed the effect of the factors of the level of debt financing needs and the manager's overconfidence by using a multiple regression model based on the sample of 87 companies listed on the Tehran stock exchange for the period of 2011 to 2020. The results indicate that managers use conditional conservatism and risk disclosure as two complementary information policies to reduce information asymmetry and agency costs. By applying more Conditional conservatism, managers improve the level of risk disclosure in proportion to the level of uncertainty perceived through risk disclosure by users to maintain consistency between quantitative and qualitative information. The debt financing needs has a negative and significant effect, and the overconfidence characteristic of managers has no significant effect on the relationship between the level of conditional conservatism and the level of risk disclosure of firms. Companies with a higher debt financing needs use more conditional conservatism than risk disclosure to reduce debt Costs. The results show that the relative costs and benefits of conservative reporting and risk disclosure affect financial reporting policies regarding risks and uncertainties. Introduction The relationship between accounting conservatism and risk disclosure is included under the relationship between recognition and disclosure decisions. The level of accounting conservatism is important in deciding the optimal level of disclosure, and Earnings Attributes are related to companies' voluntary disclosure decisions (Francis et al., 2008). Based on contractual and litigation incentives, conditional conservatism and risk disclosure are two alternative tools to reduce information asymmetry about uncertainties and reduce agency costs. As a result, managers may coordinate between these two options by considering the costs and limited benefits of each. The way managers make decisions in choosing the level of accounting conservatism and disclosure, such as earnings forecasting, has been investigated in previous studies, but no research has investigated the relationship between the level of accounting conservatism and risk disclosure as one of the types of qualitative disclosure. Hence, the question arises as to how managers coordinate the decisions of choosing the level of conservatism and risk disclosure. The purpose of this research is to explore how managers' decisions are coordinated in the two choices of conditional accounting conservatism and risk disclosure, under the influence of the debt financing needs and management characteristics in companies listed on the Tehran Stock Exchange. To cover the objectives of the research, three hypotheses including (1) the existence of a significant relationship between conditional conservatism and risk disclosure, (2) the effect of the company's debt financing needs, and (3) managers' overconfidence on the relationship between the level of conditional conservatism and the level of risk disclosure have been described and tested.MethodsResearch hypotheses have been examined by using a multivariable regression model and based on the sample of 87 companies listed on the Tehran stock exchange for the period of 2011 to 2020. The data needed for the research has been extracted from the financial statements, explanatory notes, the Management Discussion and Analysis, and the directors’ reports.The first research hypothesis is tested using equation (1).Equation (1) where RDit (the dependent variable) is the level of risk disclosure, which has been measured using the content analysis of the explanatory notes, the Management Discussion and Analysis, and the directors’ reports. Conservit (the independent variable) is conditional conservatism calculated using khan and Watts’ (2009) C-Score. Controlk,it are the control variables of the level of risk disclosure that have been selected and measured based on previous studies.The second hypothesis is tested using equation (2).Equation (2) where FIN_Needs is the variable of the need to finance through debt, which is calculated using the financing deficit criterion according to Deng et al. (2018).To test the third hypothesis, equation (3) is used to examine the effect of management overconfidence on the relationship between conservatism and risk disclosure:Equation (3) where OverConf is the manager's overconfidence variable, which is calculated based on investment-based overconfidence according to Ahmed and Duellman (2013). FindingsThere is a significant positive relationship between the level of conditional conservatism and the level of risk disclosure. The need to finance through debt has a negative and significant effect, and the overconfidence characteristic of managers has no significant effect on the relationship between the level of conditional conservatism and the level of risk disclosure of firms. Conclusion & Result The results show that managers use conditional conservatism and risk disclosure as two complementary information policies. The result conflicts with the results of Hui et al. (2009), Wang (2019), D'Augusta and DeAngelis (2020), Asadi and Bayat (2014), Nikbakht and Hajiazimi (2013) and AsadiMashizi et al. (2020). Based on the contractual and litigation demand, when companies face higher uncertainty and risk, they use more conservative accounting in their financial reporting (Dai & Ngo, 2021؛ Haque et al., 2019؛ Hsieh et al., 2019؛ Hejranijamil et al., 2020) and disclose higher risk to reduce agency costs, including the cost of debt and the possibility of lawsuits.This can be justified based on the argument of D'Augusta and DeAngelis (2020) about investors' understanding of the differences between quantitative and qualitative information. Conservatism conveys business uncertainties quantitatively and risk disclosure qualitatively conveys uncertainties to users. With a greater level of accounting conservatism, managers improve the level of risk disclosure in proportion to the level of uncertainty perceived through risk disclosure by users to maintain consistency between quantitative and qualitative information. The result is consistent with the results of Huang et al. (2014) and Nagar et al. (2019). Also, it can be explained with the assumption that the existence of reporting and risk disclosure requirements limits managers to trade-off risk disclosure and the level of conservatism, especially from the perspective of increased costs from the benefits of disclosure. Moreover, the results are consistent with the argument of Linsley and Shrives (2006) in support of mandatory risk disclosure and the research results of Dyer et al. (2017).Based on the contractual theory, companies with a higher need to finance through debt use a more conditional conservatism level than risk disclosure to reduce debt. The results show that the relative costs and benefits of conservative reporting and risk disclosure affect financial reporting policies regarding risks and uncertainties. This is consistent with the research results of Deng et al. (2018) and Michels (2017).Also, unlike previous studies (such as Ahmed and Duellman (2013) and Ramsheh and Molanzari (2014)), the results indicate that managers with overconfidence characteristics have higher risk tolerance and also provide higher levels of voluntary disclosure.Finally, the results of the research indicate that the users of financial statements should consider the financial reporting policies of a company in interpreting the information of financial reports about risks and uncertainties, because each of these policies and reporting choices in different conditions such as the need to finance through debt may affect how information is disclosed

Determination of Effect of Oral Vitamin D to Improve Ventilatory Threshold in Healthy Young Adults with Vitamin D Deficiency

Background: Many studies have shown a high prevalence of vitamin D deficiency in different communities. Due to multiple roles of vitamin D in the body, this study was aimed to determine the effect of oral vitamin D3 on ventilatory threshold-1 in a condition of vitamin D deficiency.Materials and Methods: Recent study performed on 25 healthy young adults with the serum levels of 25 Hydroxyvitamin D3 lower than 20 ng/ml, had referred to the sports medicine clinic of Taleghani Hospital of Tehran, in a one-year period (2016-2017). After primary evaluation, baseline ventilatory threshold-1 were determined by cardiopulmonary exercise testing (CPET). Then persons were treated with 50,000 IU/week of oral vitamin D3 for 8 weeks, and one week after the completion of treatment, ventilator threshold-1 was measured again, similar to the beginning conditions of the study, and its changes were studied.Results: The mean baseline ventilatory threshold-1 of participants before any intervention was 22.46 ± 6.45 (ml/kg/min), and after 8 weeks of treatment by 50000 IU/week of oral vitamin D3, increased to 26.79 ± 5.33 (ml/kg/min) at the end of study, which there was a statistically significant increase in ventilatory threshold-1 (p<0.001).Conclusion: Recent study showed that proper treatment of the vitamin D deficiency, improves ventilatory threshold-1 in healthy young adults

Comparative Outcomes of Pulpotomy in Mature Molars with Irreversible Pulpitis: A Non-Randomized Trial Evaluating Calcified and Non-Calcified Pulp Chambers

Introduction: This non-randomized clinical trial investigated the outcomes of full pulpotomy in adult molars with irreversible pulpitis, comparing those with calcified and non-calcified pulp chambers over 6 and 12 months. Materials and Methods: A total of 101 adult permanent molars with irreversible pulpitis, in individuals over 12 years old, were categorized based on pulp chamber calcification observed in radiographic images by two endodontists. Subsequently, full pulpotomy procedures were performed, achieving hemostasis, and applying a 2 mm layer of calcium-enriched mixture (CEM) cement as a pulp covering agent. After 48 hours, the setting of the CEM cement was verified, followed by the application of a layer of resin-modified glass-ionomer. The tooth was then restored using amalgam. Clinical and radiographic evaluations were conducted at 6-month and 1-year follow-ups by blinded endodontists. Success rates were compared using Fisher's exact test and logistic regression tests with a significance level of 0.05. Results: Among the 97 patients with 6-month and 1-year follow-ups, all achieved clinical success. Radiographic success rates were 99% at 6 months and 96.9% at 1 year, regardless of pulp calcification. In the 6-month follow-up, success rates were 98.07% for non-calcified pulp chambers and 100% for calcified pulp chambers. At the 1-year follow-up, success rates were 96.1% and 97.8%, respectively. Statistical analysis showed no significant difference in radiographic success rate between the two groups at both follow-ups (P>0.05). Conclusions: Full pulpotomy using CEM cement is a successful treatment for adult permanent teeth with calcified and non-calcified pulp chambers presenting signs and symptoms of irreversible pulpitis up to a 1-year follow-up. This study provides compelling evidence that vital pulp therapy can be effectively employed in the pulpotomy of calcified teeth, at least in the short term

On Supergravity Solutions of Branes in Melvin Universes

We study supergravity solutions of type II branes wrapping a Melvin universe. These solutions provide the gravity description of non-commutative field theories with non-constant non-commutative parameter. Typically these theories are non-supersymmetric, though they exhibit some feature of their corresponding supersymmetric theories. An interesting feature of these non-commutative theories is that there is a critical length in the theory in which for distances larger than this length the effects of non-commutativity become important and for smaller distances these effects are negligible. Therefore we would expect to see this kind of non-commutativity in large distances which might be relevant in cosmology. We also study M5-brane wrapping on 11-dimensional Melvin universe and its descendant theories upon compactifying on a circle.Comment: 25 pages, latex file; v2: typos corrected, Refs. adde

Roundness prediction in centreless grinding using physics-enhanced machine learning techniques

This work proposes a model for suggesting optimal process configuration in plunge centreless grinding operations. Seven different approaches were implemented and compared: first principles model, neural network model with one hidden layer, support vector regression model with polynomial kernel function, Gaussian process regression model and hybrid versions of those three models. The first approach is based on an enhancement of the well-known numerical process simulation of geometrical instability. The model takes into account raw workpiece profile and possible wheel-workpiece loss of contact, which introduces an inherent limitation on the resulting profile waviness. Physical models, because of epistemic errors due to neglected or oversimplified functional relationships, can be too approximated for being considered in industrial applications. Moreover, in deterministic models, uncertainties affecting the various parameters are not explicitly considered. Complexity in centreless grinding models arises from phenomena like contact length dependency on local compliance, contact force and grinding wheel roughness, unpredicted material properties of the grinding wheel and workpiece, precision of the manual setup done by the operator, wheel wear and nature of wheel wear. In order to improve the overall model prediction accuracy and allow automated continuous learning, several machine learning techniques have been investigated: a Bayesian regularized neural network, an SVR model and a GPR model. To exploit the a priori knowledge embedded in physical models, hybrid models are proposed, where neural network, SVR and GPR models are fed by the nominal process parameters enriched with the roundness predicted by the first principle model. Those hybrid models result in an improved prediction capability

The Trend of Comparability of Financial Reporting in the Countries of Iran and the United Arab Emirates and the Effective Factors on it

The purpose of the research is to answer the question that, despite all efforts to increase comparability at the international level, has this been achieved in the countries of Iran and the UAE? In the current research, 50 companies from Iran and 55 companies from the UAE were investigated from 2012 to 2021. To determine the comparability of financial reporting, Barth's model at the year-industry-company level, and to test hypotheses, combined/combined regression analyses and t-statistics with two independent samples were used in EViews 9 software. The research findings show that during the research period, the trend of comparability of financial reporting in the developing countries of Iran and the UAE has been increasing. The results show that the average comparability of financial reporting in Iran compared to the UAE was significantly higher. In both countries, the effect of company size on the comparability of financial reporting was positive and significant, while the effect of information asymmetry was negative and significant. In Iran, the effect of the company's growth on comparability was negative and significant, and in the UAE, it was positive and significant. In Iran, with the growth of profitability, comparability has decreased, but in the UAE, it has increased. Investigating the process of comparability in a comparative manner with other countries, as well as quantitatively calculating comparability using Barth's model, has increased the richness and development of theoretical foundations within the countr

Corporate governance and earnings quality: the behavioral theory of corporate governance (evidence from Iran)

Purpose: This study aims to examine the relationship between corporate governance (CG) and various measures of earnings quality in listed companies on Tehran Stock Exchange (TSE). The theoretical intuition for prediction of any relationship between earnings quality and CG is based on the behavioral theory and the institutional settings in Iran. Design/methodology/approach: This study used the data of 117 listed companies on the TSE for the period from 2005 to 2019. The authors use panel data regression as the main methodology, along with principal component analysis, t-test and rank-sum test. Findings: This study finds that the CG has a positive association with earnings quality. More precisely, better CG mechanisms cause lower earnings smoothness, more predictable and persistent earnings, and higher levels of timeliness, conservatism and value relevance. The relationship between CG and earnings quality is statistically and economically significant for all models. Originality/value: The findings further the understanding of the role of CG in improving earnings quality in an Islamic and emerging country. First, this study provides evidence on the relation between CG and earnings quality by focusing on the behavioral theory, which suggests that corporate decision-making is not only influenced by formal CG mechanisms, but also by informal CG arrangements. In this case, this study departs from the restrictive theories (specifically, agency theory) that are widely used in past literature. Second, this study constructs an index that fits to corporate context of Iran rather than applying indexes introduced in Anglo-American environments