Hasil untuk "Descriptive and experimental mechanics"

Rodney Martinez-Rojas, Gerardo Ruiz-Chavarria, Aristides Alejandro Legrá-Lobaina et al.

The transport of carbonated slime pulps in pipelines is important for the acid lixiviation process that has developed in the nickel extraction industry in the eastern region of Cuba. This substance is a suspension of fine particles that behaves as a viscoplastic fluid. To address the lack of research conducted on carbonated slime pulps, we carried out an experimental investigation of the rheological properties of this substance over varied operational conditions. As the shear rates involved in the experiments covered more than two orders of magnitude, we fitted the flow curves to the Herschel–Bulkley model, which has been used in the past to model different suspensions. Through data analysis, we observed a transition in rheological behavior at a solid particle concentration of about 30%. Based on the trend of the flow curves, we built an empirical model to predict the rheological properties of slime pulps. In this model, the flow properties of the substance depend on the concentration of solid particles, the pH and the polydispersity index. Our empirical model exhibits high accuracy in predicting the flow properties of carbonated slime pulps. The results can be used to improve the efficiency of industrial processes involving these mineral suspensions.

Mohammad Umar, Bharat Tripathi

Performance in web applications is a key aspect of user experience and system scalability. Among the different techniques used to improve web application performance, caching has been widely used. While caching has been widely explored in web performance optimization literature, there is a lack of experimental work that explores the effect of simple inmemory caching in small-scale web applications. This paper fills this research gap by experimentally comparing the performance of two server-side web application configurations: one without caching and another with in-memory caching and a fixed time-tolive. The performance evaluation was conducted using a lightweight web server framework, and response times were measured using repeated HTTP requests under identical environmental conditions. The results show a significant reduction in response time for cached requests, and the findings of this paper provide valuable insights into the effectiveness of simple server-side caching in improving web application performance making it suitable for educational environments and small-scale web applications where simplicity and reproducibility are critical.

Daichi Yamashita, Frederick James Henderson, Yuko Ishida

Background/Objectives: This study evaluated the reliability and validity of three methods to measure jump height during countermovement jumps performed with (CMJ_AS) and without (CMJ_NAS) arm swing: (1) an impulse–momentum method with force platforms (FP_imp), (2) a flight time method with force platforms (FP_time), and (3) an inertial measurement unit (PUSH Band 2.0; PUSH2). Methods: Eighteen physically active men performed CMJ_AS and CMJ_NAS on force platforms while wearing PUSH2 over two days. Besides jump height, we computed intraclass correlation coefficients (ICC) and the absolute and relative increases in jump height due to arm swing, compared to CMJ_NAS. Results: The reliability of intra-session, inter-session, and concurrent measures were good to excellent (intra-session ICC_2,1 = 0.957–0.979, inter-session ICC_2,1 = 0.806–0.990, concurrent ICC_3,1 = 0.940–0.973) for CMJ_AS and CMJ_NAS heights, in all three methods. The three methods showed high to very high reliability for both the absolute and relative indices of arm swing contribution (ICC_2,1 = 0.649–0.812). FP_time significantly overestimated CMJ_NAS height relative to FP_imp (<i>p</i> < 0.01). The absolute index of arm swing contribution was similar in FP_imp and FP_time (<i>p</i> = 0.38) but higher in PUSH2 (<i>p</i> < 0.01), indicating that arm swing amplified overestimation. Conclusions: All three methods demonstrated high reliability for jump height measurements, but FP_time and PUSH2 misestimated jump height depending on jump modalities. Caution is advised when assessing the absolute and relative contribution of arm swing, because errors in CMJ_NAS and CMJ_AS height measurements can affect these values and their interpretation.

Amine Benmoussa, José C. Páscoa

In industrial mixing processes, impeller design, rotational speed, and mixing conditions play a crucial role in determining process efficiency, product quality, and energy consumption. Optimizing the performance of stirring systems for non-Newtonian fluids is essential for achieving better results. This study examines the hydrodynamic and thermal performance of stirring systems for viscoplastic fluids, utilizing close-clearance anchor impellers with chamfered angles of 22.5°, 45°, and 67.5° in cylindrical, flat-bottom and unbaffled vessels. Through a comprehensive comparative analysis between standard and chamfered impeller designs, the study evaluates their efficacy in overcoming yield stress, enhancing flow dynamics, and improving thermal homogeneity. The effects of Reynolds number and yield stress on the hydrodynamic and thermal states are analyzed. The results indicate that the 67.5° chamfered impeller significantly improves flow distribution and minimizes dead zones, particularly in critical areas between the anchor blades and vessel walls, where mixing stagnation typically occurs. It also enhances vertical mixing by promoting a broader shear spread along the vessel height and a more uniform temperature distribution. These insights contribute to the development of more efficient agitation systems, applicable across various industries handling complex fluids.

Hernán Gustavo Solari, Mario Alberto Natiello

In Part I we constructed the Quantum Mechanics of a charged unitary entity and prescribed the form in which such a particle interacts with other charged particles and matter in general. In this second part we extend the description to the hydrogen atom testing the correctness and accuracy of the general description. The relation between electron and proton in the atom is described systematically in a construction that is free from analogies or ad-hoc derivations and it supersedes conventional Quantum Mechanics (whose equations linked to measurements can be recovered). We briefly discuss why the concept of isolation built in Schrödinger's time evolution is not acceptable and how it immediately results in the well known measurement paradoxes of quantum mechanics. We also discuss the epistemic grounds of the development as well as those of conventional Quantum Mechanics.

Ahmad Morsel, Filippo Masi, Emmanuel Marché et al.

We present a novel experimental setup called miniBLAST, which enables systematic and repeatable laboratory tests of structures subjected to blast loads. The explosive source is based on the discharge of high electrical loads on a thin conductor, producing repeatable blast-type shock waves of controlled intensity. Conducting blast experiments under safe laboratory conditions offers significant advantages over large-scale experiments, which are expensive, require specialized personnel, are limited in number, and face repeatability issues. In this work, we provide a comprehensive description of the setup's design rationale and technical characteristics. Moreover, we place particular emphasis on the installation phases, safety, and metrology. The explosive source is analyzed and the signature of blast shock waves is retrieved. Finally, we present an example of a masonry wall subjected to blast loads of varying intensity. We then report its dynamic response in three dimensions and at different time instances. This new experimental setup offers a cost-effective, safe, and repeatable method to study structural dynamics under blast loads, with results that can be upscaled to real structures. It also aids in evaluating numerical models and lays the groundwork for further investigations into blast effects and mitigation.

Junaid Junaid, F. Firman

The study aims to find out whether or not the use of UVIOPro is effective to improve the students’ writing skill, particularly in terms of content, organization, and mechanics. This study applied a Quasi-Experimental design. The sample of this study was the second semester students of English Education department at Faculty of Teacher Training and Education at University of Muhammadiyah Makassar in academic year 2014/2015. Therefore, the sample was determined with a cluster random sampling by applying a lottery technique. Hence, it consisted of 60 students divided in two groups. The data were collected through writing test, which consisted of pretest and posttest. The data were analyzed by using descriptive and inferential statistics through SPSS version 20. The findings show that the students’ writing skill, particularly in terms of content, organization, and mechanics improved after giving the treatments. The results of t-test analysis for the students’ score improvement in terms of content and organization in experimental and control groups reveals that Sig. (2-tailed) is less than (α) = 0.05. Based on the findings, it can be concluded that the use of UVIOPro in teaching writing was effective to improve the students’ writing skill in terms of content, organization, and mechanics.

Gessler Lyndon Medrano Sánchez, Royer David Llanos Marín, Tulio Edgar Guillén Sheen

. The objective of this research is to determine the physical and mechanical properties of artisanal brick with natural aggregate containing iron particles, 2022. The methodology used according to its purpose is considered applied, with a quantitative approach and experimental design, descriptive in scope and insofar as the study period is cross-sectional, selecting a sample of 300 bricks made with the addition of 10%, 25%, 50% and 75% of natural aggregate containing iron particles. To achieve the objective of the investigation, the physical properties of the Standard Sample (MP), of the natural aggregate containing iron particles (MH), of the samples with increases of 10%, 25%, 50% and 75% will be previously reduced. from (MH); After carrying out the soil mechanics tests, we proceeded with the elaboration of artisan bricks. Subsequently, the study units were subjected to laboratory tests to determine the physical and mechanical properties of the handmade brick made with the Standard Sample (MP) and with the addition of 10%, 25%, 50% and 75% of (MH). The results showed that the sample with an increase of 10% of MH, satisfies the requirements of the NTP-E.070 of Masonry, in terms of dimensional variation, warpage and absorption; Likewise, the compressive strength in units increases by 36.40% and the compressive strength in masonry piles by 4.69%, in relation to the NTP E.70 for class 1 bricks; and in relation to the standard sample, the increase was 50.80% and 53.43%.

Israwati Nurhidayah J, Eka Prabawati Rum, Uyunnasirah Hambali

This study aimed to find out whether or not Task-Based Language Teaching method improve the writing skills of class X AP students at SMK Muhammadiyah 2 Bontoala in terms of grammar and mechanics. The research method used was quantitative with a pre-experimental design. The population in this study were students of SMK Muhammadiyah 2 Bontoala. The number of samples used was 20 students and the sample class were selected using a purposive sampling technique.Based on the results, the pre-test score of students' writing skills in terms of grammar was 65.8 and the post-test score was 81.4. While the Pre-test score of students' skills in terms of mechanics was 64.0 and post-test is 83.0. After analyzed the results of the pre-test and post-test data, the researcher found that in writing skills, p-value (0.000) less than α (0.05), this indicates that the null hypothesis is rejected and alternative hypothesis is accepted.The researcher concluded that Task-Based Language Teaching through descriptive text at SMK Muhammadiyah 2 Bontoala improved students' writing skills. There is a significant difference in students' writing skills in terms of grammar and mechanics with the use of Task-Based Language Teaching methods.

Elisabeth Sinaga, Deski Ramosta, Simanjuntak et al.

The objective of the research was designed to find out the students‟ ability in writing descriptive text by using HOTS questions at 8th grade in SMA Negeri 3  Pematangsiantar. It deals with content, organization, vocabulary, language use, and mechanics. The problem of this research was “to what extent does the students writing ability based on the application of HOTS questions? This research was designed as a quantitative research. The sample of this research was taken from two classes that consist of 66 students (33 students in experimental group in class 10 IPA 7 and 33 students in control group in class X IPS 1. Then quantitative data were obtained from the students‟ writing score of pre-test and post-test.  The research finding of this research showed that there was an improvement on the students‟ writing ability in descriptive text based on HOTS questions. It can be seen from the mean score of pretest was 52.75 and the mean score of post-test was 80.51.  And the researcher also found that t-test is higher than t-table it can be seen from df: 64 (33+33 -2) with the t-table is 1.25 and the level of significance 0.05. It shows that t-test is higher than t-table (1.27 > 1.25). After analyzing the data, the researchers concluded that using HOTS questions could develop the students‟ writing ability in descriptive text at 10th grade in SMA Negeri 3 Pematangsiantar.

Rubén Darío Sirpa Espinoza

In this work, the generic and specific skills required by the labor market for graduates in Automotive Mechanics are determined. It was framed in a quantitative research, the study was of a propositional descriptive type, it included a non-experimental, transectional design. A survey has been carried out in which the following results were found: 60% of academics consider it important that graduates demonstrate theoretical-practical knowledge in automotive mechanics. Furthermore, 80% of them believe that professional performance should be in line with technological advances in the field. 100% of academics also emphasize the importance of continuing training programs. In response to these findings, the “Diploma in modern technologies in gasoline and diesel engines in automobiles” has been designed in a blended format, aimed at practicing professionals.

L. Lopez

This study aimed to evaluate and validate the developed numeracy mobile game to help improve the performance of junior high school students on the operations of integers in a public national high school in Antipolo City, the Philippines.  The researcher used experimental and descriptive research designs in the study.  The sources of data in this research were eighty (80) JHS students, twenty (20) from each grade level, from Old Boso-Boso National High School. Other respondents were the forty (40) teacher respondents consisting of twenty (20) experts and twenty (20) math teachers from Schools Division of Antipolo. The statistical tools used in this study were the frequency, percentage, weighted mean, independent-samples t-test, and paired t-test.  It was revealed that there was no significant difference between the evaluations of the two groups of respondents on the developed numeracy mobile game in operations of integers in terms of game mechanics, visual aesthetic design, narrative design, incentive system, musical scores, and content and skills. It is recommended that the user interface of the game needs some enhancements like the controls for arrows up and down and improve the tutorial part before starting the real game or at the start of every level.

Anjana. Sharma, R. Kalia

Introduction: “Body mechanics” is a term used to describe the ways we move and go about in our lives. It includes how we hold our body while sitting, standing, lifting, bending, carrying, or moving. Poor body mechanics can often lead to poor body posture, back pain, and related discomfort. Workers in industries and offices are exposed to various types of risk factors such as lifting heavy items, bending, reaching overhead, pushing and pulling heavy loads, working in awkward body postures, and performing the same or similar tasks repetitively, causing morbidity. Taking care of the back is a lifelong project, and use of proper body mechanics is an effective way to maintain health and fitness of the back. Objective: To assess the posture of adults at their workplace with an aim to develop a health education package on body mechanics. Methodology: Non-experimental descriptive design was used for the study. The study was conducted among 50 subjects from various organizations at Kurali, Punjab. Sociodemographic data sheet and an observation checklist were used to observe the body mechanics practices of the subjects. Results: The findings of the study revealed that 27 (54%) subjects had good body mechanics practices, 17 (34%) had average practices, whereas 6 (12%) had poor body mechanics practices. Conclusion: Only half of the workers were practicing good body mechanics; hence, there is a need to educate the workers regarding good practices.

Mykhailo Sukach, Svitlana Komotska

В природному стані тиксотропні явища в ґрунтах найбільш часто виникають при зовнішніх навантаженнях динамічного характеру: землетрусах, вібрації від транспортних засобів, що рухаються, працюючих машин і механізмів. Відомості про дослідження тиксотропії ґрунтів свідчать про те, що при динамічному навантаженні зменшувати міцність і переходити в рідкий стан можуть дисперсні ґрунти різного типу, генезису і віку. Вплив динамічного навантаження особливо суттєвий у випадку слабоущільнених і водонасичених піщаних та глинистих ґрунтів. При динамічному навантаженні може відбуватися як ущільнення ґрунту і відповідно підвищення його міцності, так і зменшення міцності. Частіше доводиться стикатися з процесами зменшення міцності і розріджування ґрунтів при динамічному впливі. Найбільш вивчені процеси, що відбуваються у водонасичених пісках. Стан розрідження при вібрації виникає внаслідок руйнування контактів між окремими зернами, тривкість піщаного ґрунту падає практично до нуля. Після зняття вібронавантаження піщинки під впливом власної ваги переміщуються вниз, викликаючи стискання рідкої фази. Чим більше піски містять тонкодисперсних часток і органічної речовини, тим довше вони зберігають рідиноподібний стан, тим повільніше відбувається відтискання води і ущільнення. Можливість розрідження піщаних ґрунтів визначається не стільки природною пористістю, скільки напруженим станом ґрунту і характером вібровпливу.

Eduardo Martín-Martínez

Informal collection of lecture notes introducing quantum mechanics in phase space and basic Gaussian quantum mechanics.

James P. Finley

A generalized Euler equation of fluid dynamics is derived for describing many-body states of quantum mechanics. The Eulerian Eq. can be viewed as representing the interaction of two substates, where each substate has its own velocity and pressure fields. These field quantities are given by maps of the wavefunction. For one-body systems, the Eulerian Eq. can model either a fluid or particle description of quantum states. The generalized Euler Eq. is shown to be the gradient of an equation representing the total-energy of the two substates, having two energy fields. This total-energy Eq. is a generalization of the Bernoulli Eq. of fluid dynamics. The total-energy Eq., along with a continuity-equation, is equivalent to the time-dependent Schroedinger Eq. An equation is also derived that is equivalent to the main equation of Bohmian mechanics with additional identifications: The quantum potential of Bohmian mechanics is given as a sum of a kinetic energy and pressure fields. Also, the time derivative of the wavefunction phase is replaced by an energy field. In the formalism, field quantities are identified from their placement in equations of classical mechanics and separately, by definitions that involve the wavefunction and operators of quantum mechanics. This approach yields, unintended, and unknown energy and pressure fields. These fields, however, are shown to satisfy a continuity Eq., an equation that is equivalent to the other equation of Bohmian mechanics. It is also demonstrated that energy conservation holds for both of these energy fields, if the wavefunction is a linear-combination of eigenvectors, where the eigenvectors can be nondegenerate. A detailed investigation is given on the possible behavior, or source, of an electron that has one of the velocity fields. Alternate formulae for this velocity fields are also considered.

Fitri Ramadhani Harahap

This research was aimed to develops teaching writing by using drill method as method in teachingwriting descriptive paragraph. This study was conducted applying Nana Sudjana (1989:86) theory.The research took place at MTs.Swasta IRA Medan. The sample consisted of class VII. Theinstruments employed in this study experimental research which consist of pre-test and post-test..The findings of the study were the quality of the developed technique as media viewed from theexperts is very good (88 %). Most students gave positive responses. Most students said that themethod was interesting and it could help them to write descriptive texts easily. The results of thetest show that the method improved their ability in writing descriptive paragraph (average score:80, 12).The scoring system was based on five aspects; namely content, organization, vocabulary,language use, mechanics. Therefore, the writer suggests that English teachers develop method asone of the creative way to improve the students’ ability in writing descriptive texts.

Mary K. Ruetten

L. Lopez

Danqi Li, Yingchun Li, M. Asadizadeh et al.

Abstract Many experimental studies have been carried out to characterise the mechanical performance of cable bolts under axial or shear loading. The common limitation in all these studies is that only single-variate descriptive analysis was included leading to an insufficient understanding of interactive influences of a range of parameters on the mechanical performance of cable bolt. Also, defining a reasonable number of experiments for the testing program that includes wide range of parameters has been a challenge for the scholars and practitioners. Thus, to address these limitations in a sound and logical manner, two statistical techniques being Taguchi and Response Surface Methodology (RSM) were introduced to demonstrate their effectiveness for a proper design of experiments leading to a minimum number of tests without compromising the output quality. Such a task was performed on the data reported in the literature. In addition, the quantitative post-data processing was conducted using Analysis of Variance (ANOVA). To be specific, ANOVA was mainly performed to quantify the contribution of different independent parameters (e.g. confining medium and grout strengths as well as borehole dimeter) on the dependent ones (e.g. peak and residual loads as well as the initial stiffness) individually and interactively. RSM was also used for the post-data multivariate statistical analysis. Finally, it was concluded that with the aid of Design of Experiments techniques such as Taguchi it is feasible to develop a minimum number of experiments to obtain the most representative tests results without compromising the quality of research outcome along with some quantitative post-data processing using ANOVA. Also, it was demonstrated that one of the most important specifications of RSM is to provide the quantitative and visual interactive effects of independent parameters on the mechanical performance of different cable bolts using multiple regression modelling.