Performance Test Research Articles

Developing learning and training within industry model to improve work readiness of vocational high school students

<span lang="EN-US">Unemployment is still a national priority that needs to be addressed. In 2022, vocational high schools in Indonesia had the highest open unemployment rate. The highest open unemployment rate is a result of vocational high school students’ insufficient work readiness. Therefore, this research aims to develop a learning and training within industry (LTWI) model, and to evaluate the model’s efficacy in increasing vocational high school students’ work readiness. The research employed a research and development (R&D) design by Richey and Klein with the phases of needs analysis, internal validation, and external validation. There were 12 teachers and 89 students from the automotive engineering department at Muhammadiyah 1 Pakem Vocational High School and 1 Puring Vocational High School, as well as six instructors from the automotive industry: GAS Auto Service, Automotive Jogjakarta Center (OJC), Bengkel Barokah, and RND Auto Service, participated in the research. Data collection strategies adopted were interviews, questionnaires, and performance tests. The data were descriptively evaluated, and the conclusions were drawn using a categorization formula. With an average score of 3.43, the LTWI model can be used to learn very well. With an average final score of 3.32, the efficacy of the LTWI learning model falls into the category of “very good”. The LTWI model can be applied effectively to learning in vocational high schools since it has a positive influence on students’ work readiness.</span>

Highly durable perfluorosulfonic acid proton exchange membrane by combining inorganic free radical scavengers and organic antioxidants

In this work, a new type of complex was constructed by coordinating quercetin (QC) with cerium (Ce) ions. This complex was introduced into perfluorosulfonic acid resin (PFSA) to fabricate a proton exchange membrane. The coordination process prevented the formation of ion cross-links between cerium and sulfonic acid groups in PFSA, thereby keeping proton conductivity and fuel cell performance of membrane samples at a high level. Due to the insolubility of quercetin in water, its coordination with cerium minimized cerium migration, providing long-lasting resistance to free radicals. The effects of additives on PFSA membrane properties were investigated by measuring IEC, water uptake, swelling ratio, and proton conductivity. Fenton degradation experiments and membrane electrode assembly performance tests was conducted simultaneously. The results demonstrated that compared to the addition of quercetin or cerium alone, the use of QC-Ce increased the proton conductivity by 23.70% after 24-h Fenton degradation and lowered fluoride release by 58.29%. Meanwhile, the PFSA/QC-Ce composite membrane samples maintained an open circuit voltage of 0.935 V and a maximum power density of 668.15 mW cm−2 after 96 h of open circuit voltage hold testing.

Developing a hetero-intelligence methodological framework for sustainable policy-making based on the assessment of large language models

This work delves into the increasing relevance of Large Language Models (LLMs) in the realm of sustainable policy-making, proposing an innovative hetero-intelligence framework that blends human and artificial intelligence (AI) for tackling modern sustainability challenges. The research methodology includes a hetero-intelligence performance test, which juxtaposes human intelligence with AI in the formulation and implementation of sustainable policies. After testing this hetero-intelligence methodology, seven steps are rigorously described so that it can be replicated in any sustainability planning related context. The results underscore the capabilities and limitations of LLMs, underscoring the critical role of human intelligence in enhancing the efficacy of hetero-intelligence systems. This work fulfils the need of a rigorous methodological framework based on empirical steps that can provide unbiased outcomes to be integrated into sustainable planning and decision-making processes.-Assesses LLMs’ limitations and capabilities regarding sustainable planning issues-A replicable methodology is proposed based on the combination of both human and artificial intelligence-It proposes and systematises the integration of a hetero-intelligent approach into the formulation of sustainability policies to be more efficient and effective

Principle of the electromagnetic testing based on the varied frequency domain and its realization

With the development of modern industry, the types and quantities of industrial equipment are increasing. In the long-term production process, various failure modes such as corrosion and cracks will occur, therefore the workload of inspection will increase dramatically. It is extremely urgent to study the combined non-destructive testing (NDT) technology and develop corresponding multi-functional instruments to achieve rapid inspection. In this paper, an electromagnetic testing principle based on the varied frequency domain is proposed. In the first place, spatial uniformity and spatial periodic static fields are generated by the arrangement of the permanent magnetizers, these static fields are fields with different spatial frequencies. In the second place, dynamic fields with different frequencies are generated by different frequencies excitations. Under the time-space electromagnetic field coupling, a new combined electromagnetic testing principle of magnetic flux leakage (MFL), guided wave (GW) and electromagnetic acoustic transducer (EMAT) is proposed. The MFL testing method can be realized based on the uniform static field, GW based on the interaction of spatial periodic static field and low frequency dynamic field, while EMAT based on the combination of uniform static field and high frequency dynamic field. According to the above principle, a multi-functional instrument is developed, which includes a medium-low frequency excitation unit for GW, a high frequency excitation unit for EMAT, corresponding receiving amplifiers for GW/EMAT/MFL, and USB-based data transmitters. Finally, the relevant performance tests are carried out, which laid the foundation for field application.

Design and development of model for proton exchange membrane fuel cell

Fuel prices are rising, and fossil fuel resources are depleting. This fuel is consumed by conventional fuel vehicles, which contributes to increased greenhouse gas emissions and air pollution. Various vehicle technologies have been introduced in modern times. Among these innovations, fuel cell vehicle technology stands out due to its ease of use, robustness, and simplicity. The primary energy source for this system is hydrogen. Fuel cells use hydrogen to generate electricity through a chemical process that does not involve combustion. The purpose of this paper is to describe the design and development of a simulation model for a fuel cell (proton exchange membrane type) vehicle using mathematical equations and the MATLAB/Simulink R2020a software, taking into account all voltage losses and temperature variations of the proton exchange membrane (PEM) type fuel cell. The designed model is validated in two ways: first by generating V-I characteristics for the designed PEM-type fuel cell, and then by performing a performance test in Simulink using the driving cycle on one of the fuel cell vehicles. The obtained simulated results are nearly identical to the expected results, and the designed PEM-type fuel cell performed well in all real-time driving cycle test conditions.

Anti-seepage performance and underlying mechanism of carboxymethyl cellulose sodium-modified bentonite in hydraulic engineering applications

Bentonite is widely utilized in hydraulic engineering projects. However, its performance may deteriorate under extreme environmental conditions. Hence, we aim to develop a sodium carboxymethyl cellulose (CMC)-modified bentonite and investigate its anti-seepage performance. The results showed that the 10% CMC-modified bentonite exhibited the best performance. Compared with unmodified bentonite, the expansion index of 10% CMC-modified bentonite significantly increased to 40 mL/2 g, indicating a high water absorption capacity and expansion property. Moreover, it showed a significant decrease in permeability coefficient (3.72×10−11 m/s) and an increase in porosity (1.90), indicating its excellent anti-seepage effect. Furthermore, under unconventional environmental conditions and long-term performance tests, the 10% CMC-modified bentonite shows improved stability compared to the unmodified bentonite. Therefore, it can be concluded that this study provides support for the utilization of CMC-modified bentonite in anti-seepage engineering and hydraulic engineering applications.

Evaluation of Mechanical Joint Structural Performance through Actual Performance Testing of PC Connections

Evaluation of Mechanical Joint Structural Performance through Actual Performance Testing of PC Connections

Development and validation of a hysteretic model for a novel self-centering friction damper

This study aimed to develop a novel self-centering friction damper (SC-FD) consisting of the winding rope, the friction shaft and the self-centering spring. The theoretical model and equations for the mechanical properties of the SC-FD were derived. Then, the dynamic performance test of the SC-FD and finite element simulation were done to validate the theoretical mechanical model of the SC-FD. Finally, the influence of the main parameters on the dynamic performance of SC-FD was analyzed and design recommendations were made. The study showed that the SC-FD exhibited stable flag-type hysteretic behavior, with good energy dissipation capability and self-centering performance. The theoretical model and equations derived in this study can be used to predicate the behavior of the SC-FD accurately. The parameters, such as the initial inclination angle of the winding rope, winding turns of the winding rope and the stiffness of the self-centering spring and so on, had significant influences on the mechanical performance of SC-FD, which should be optimized in the designing of the SC-FD in order to get excellent mechanical performance.

Rotational angle and speed detection via a chip-scale GaN optoelectronic device

In this paper, a new method for rotational angle and speed measurements is proposed by integrating a GaN optoelectronic chip with a stepped disc. The optoelectronic chip that integrates a light-emitting diode (LED) and a photodiode (PD) is fabricated by wafer-level microfabrication. The disc is designed with a spiral staircase shape, and has increasing thickness distribution along the circumferential direction. The sensing mechanism is that the optoelectronic chip measures angle-dependent intensity change of the light reflected off the stepped disc. Through a series of performance tests, the chip is highly sensitive to a continuous rotation from 0∘ to 360∘, and produces photocurrent to indicate the rotational angle and speed. A rotational speed up to 5000 rpm is measured with a relative error less than 1.27%. The developed sensing architecture provides an alternative solution for constructing a low-cost, miniaturized, and high-efficiency rotational angle and speed sensing system.

Ionic liquid coating for charge mitigation of solar modules in space: Electron microscopy on insulating nanosphere lithography patterned surfaces

Surfaces of satellites and spacecrafts are exposed to high energy charged particles from the solar wind, especially during space weather events. This can lead to differential charging, which is a common reason for hardware degradation and sensor errors. Solutions like coatings are required to avoid excessive cost and weight. Mimicking the electron part of space-like environments in ultra-high vacuum (UHV) chambers can be achieved by using electrons emitted by a scanning electron microscope (SEM). As a performance test for the discharge capabilities we use the quality of electron microscopy images on otherwise insulating substrates such as glass, structured by nanosphere lithography and coated with an ionic liquid (IL). Additionally, the surface potential was measured by Kelvin Probe Force Spectroscopy. The IL film (BMP DCA) was applied ex situ and a thickness of 12.8 ($\pm$0.8)\,nm was determined by reflectometry and confirmed by dynamic atomic force microscopy. Such a film of ionic liquid would lead to additional mass of below 20\,mg and negligible additional material costs. The light absorption and influence of ionic liquid coatings on the current output of an actual solar cell were investigated. The results indicate, that these coatings are promising candidates for surface charge mitigation with a high potential for application

Novel design of Sn4P3@NxC electrodes and their electrochemical properties

Tin phosphide (SnxPy) is recognized as one of the most promising anode materials for lithium-ion batteries due to its exceptionally high theoretical capacity. However, its application is hampered by significant volume expansion during charge-discharge cycles and inferior electrical conductivity. Proper structural design placs a pivotal role in addressing these challenges, paving the way for high-performance anode materials. This study introduces a nitrogen-doped carbon-coated Sn4P3 nanosphere with a core-shell structure, employing dopamine as the nitrogen source. This innovative approach, utilizing template removal and solid-phase phosphorization, results in both the core and shell acting as active materials, thereby enhancing the volumetric energy density of the electrode. The internal voids within the shell layer mitigate volume expansion during charge-discharge cycles, while the presence of the nitrogen-doped carbon layer maintains the material's stability throughout cycling and improves its electrical conductivity. Electrochemical performance tests confirm the outstanding energy storage capability of this material, with an initial Coulombic efficiency reaching up to 73.6 %. Furthermore, it maintains a stable capacity of 585 mAh g^-1 after 1200 cycles at a current density of 2 A g^-1. This research offers a design paradigm for the development of novel energy storage materials.

Modulation of EEG Signals by Visual and Auditory Distractors in Virtual Reality-based Continuous Performance Tests.

Compared to traditional continuous performance tasks, virtual reality-based continuous performance tests (VR-CPT) offer higher ecological validity.While previous studies have primarily focused on behavioral outcomes in VR-CPT and incorporated various distractors to enhance ecological realism, little attention has been paid to the effects of distractors on EEG. Therefore, our study aimed to investigate the influence of distractors on EEG during VR-CPT. We studied visual distractors and auditory distractors separately, recruiting 68 subjects (M=20.82, SD=1.72) and asking each to complete four tasks. These tasks were categorized into four groups according to the presence or absence of visual and auditory distractors. We conducted paired t-tests on the mean relative power of the five electrodes in the ROI region across different frequency bands. Significant differences were found in theta waves between Group 3 (M = 2.49, SD = 2.02) and Group 4 (M = 2.68, SD = 2.39) (p < 0.05); in alpha waves between Group 3 (M = 2.08, SD = 3.73) and Group 4 (M = 3.03, SD = 4.60) (p < 0.001); and in beta waves between Group 1 (M = -4.44, SD = 2.29) and Group 2 (M = -5.03, SD = 2.48) (p < 0.001), as well as between Group 3 (M = -4.48, SD = 2.03) and Group 4 (M = -4.67, SD = 2.23) (p < 0.05). The incorporation of distractors in VR-CPT modulates EEG signals across different frequency bands, with visual distractors attenuating theta band activity, auditory distractors enhancing alpha band activity, and both types of distractors reducing beta oscillations following target stimuli. This insight holds significant promise for the rehabilitation of children and adolescents with attention deficits.

Development and mechanism research of hydrophobic associative polymer drag reducing agents

ABSTRACT The challenge of insufficient proppant transportation capacity in slick water remains unresolved. To tackle this concern, a hydrophobically associating water-soluble polymer (HAWP), characterized by a low molecular weight (MW) of 8.11 × 105 g/mol, was successfully synthesized via a photo-initiation method. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The results show that in comparison to conventional drag reducers in slick water with an average MW of approximately 1 × 107 g/mol, HAWP demonstrates significantly reduced MW. The rheological test results indicate that upon addition of sodium dodecyl benzene sulfonate (SDS, 200 mg/L) to the HAWP solution (0.3 wt%), the storage modulus experienced a substantial increase from 0.14 Pa to 7.42 Pa, demonstrating enhanced mechanical properties. Meanwhile, drag reduction (DR) tests showed that the efficiency of drag reduction achieved by the polymer system (PS) drag reducer was comparable to that of conventional linear polymers. This research achievement effectively addresses the challenges of low molecular weight and resistance reduction encountered in previous endeavors.

Examining the association between balance self-efficacy and virtual balance performance in individuals with stroke: a cross-sectional study

ABSTRACT Background Balance self-efficacy is a strong predictor of fall risk after stroke and is related to performance on balance and walking tests. The use of telerehabilitation for delivering stroke rehabilitation has increased in recent years and there is a need to adapt common clinical assessments to be administered in virtual formats, but the association between balance self-efficacy and virtually administered clinical tests of balance performance has yet to be established. This study examined the association between the Activities-specific Balance Confidence (ABC) Scale and virtually administered Timed Up and Go (TUG), Tandem Stand, and Functional Reach tests (FRT) in individuals with stroke. Methods This was a secondary analysis of baseline data from two telerehabilitation trials with individuals with stroke. All assessments were administered by trained physical therapists through videoconferencing software. Multivariate regression analyses were used to examine the associations between the ABC scale and TUG test, Tandem Stand test, and FRT, adjusted for age and number of comorbidities. Results Data from 51 participants (n = 11 female, median age = 64 [IQR: 18] years, 9.3 ± 4.6 months poststroke) were analyzed. The ABC scores were associated with TUG (R2 = 0.56, F(3,47) = 20.26, p < 0.01), but not Tandem Stand (R2 = 0.18, F(5,45) = 1.93, p = 0.11) or FRT (R2 = 0.14, F(3,47) = 2.55, p = 0.07) tests. Conclusion We observed associations between the ABC scores and virtual TUG, but not with Tandem Stand or FRT, which may be attributed to the context-specificity of balance self-efficacy. As virtual administration of outcomes assessments becomes part of common practice in stroke rehabilitation, our study supports the use of virtually administered TUG in stroke.

Employee Engagement on Behavioral Performance: Study on public organization in Bandung, Indonesia.

The demand for adapting new skills is an essential factor for employees to continue to be able to compete competitively. This research aims to determine employee commitment to Behavioral Performance. Researchers conducted a survey of government agency employees to test the influence of employee commitment on Behavioral Performance, conducting first-order and second-order tests. The research respondents were 87 employees at three government agencies in Bandung. The research results indicate that employees firmly commit to improving Behavioral Performance. The research implications suggest that government agencies should provide opportunities for employees to increase their commitment by adopting new skills, strengthening employee commitment through relevant direction strategies, providing constructive feedback, and emphasizing the consequences if duties and obligations are not fulfilled to provide optimal performance.

Comparison of shock absorption capacities of three types of mouthguards: A comparative invitro study.

3D printing processes can be used to manufacture custom-made mouthguards for sports activities. Few studies have compared the impact performance of industrial-created mouthguards with that of custom-made mouthguards manufactured by thermoforming or 3D printing. The objective of this invitro study was to compare the shock absorption capacities of custom-made mouthguards manufactured by 3D printing with industrial mouthguards and thermoformed ethylene vinyl acetate (EVA) mouthguards. For each type of mouthguard, eight samples were produced. 3D-printed mouthguards were manufactured using digital light processing technology. Each mouthguard was subjected to an impact performance test defined by the standard AFNOR XP S72-427, which evaluate maximum deceleration and force transmitted during impact. The thickness of each mouthguard before and after a series of five impacts was measured at the impacted inter-incisal area. The mean maximum decelerations during impact ranged from 129 to 189 g for industrial mouthguards, 287 to 425 g for thermoformed EVA mouthguards, and 277 to 302 g for 3D-printed mouthguards. The mean reduction in mouthguard thickness at the impact zone after five tests was 1.2 mm for industrial mouthguards, 0.6 mm for 3D-printed mouthguards, and 2.2 mm for thermoformed EVA mouthguards. Custom-made 3D printed mouthguards showed slightly better shock absorption ability than thermoformed mouthguards with respect to the indicator proposed in XP S72-427. They seemed to combine the practical advantages of thermoformed mouthguards in sports with better shock absorption capacity and lower cost. Furthermore, they had the least thickness variation during the test, and their shock absorption capacity was the least affected by repeated mechanical tests. Other types of 3D-printing resin materials that will become available must continue to be tested for shock absorption to provide the best protection to users at low cost.

Association between intra-individual variability and prefrontal cortex activity measured by functional Near Infrared Spectroscopy (fNIRS) in children with ADHD

ABSTRACT This study uses fNIRS to determine whether there is a difference in the relationship between intra-individual variability and frontal lobe activity between ADHD patients and typically developing children. A total of 28 subjects (14 in ADHD patient group and 14 in control group) participated in this study. The subjects were tested for K-SADS and intelligence, and then the frontal lobe activity of the subjects was measured by continuous performance test, using functional near-infrared spectroscopy (NIRSIT). Processing speed index was significantly lower in the ADHD patient group than in the control group (p = .04). The CPT test results showed a positive correlation in the activity of the right dorsolateral prefrontal region in the patient group, but not at a statistically significant level. In the control group, activity showed a significant level of negative correlation with commission and hit reaction time standard deviation (p = .023; p = .063 respectively). In contrary to ADHD patient group, activation of the right dorsolateral prefrontal area was significantly correlated with reduction of intra-individual variability. This result showing that the relationship between activation of the right dorsolateral prefrontal area of the ADHD patient group and intra-individual variability shows a different pattern from typically developing children.

High throughput screening of promoted bimetallic catalysts supported on alumina for production of light olefins via Fischer-Tropsch synthesis with artificial neural network and response surface methodology

The production of light olefins via Fischer-Tropsch Synthesis (FTS) was investigated by both experimental and modeling studies. Experimental studies were conducted by employing promoted FeCo/α-Al2O3 (FeCo) bimetallic catalysts. The Response Surface Methodology (RSM) and Artificial Neural Network (ANN) methods were used in modeling. Specifically, effects of the types and concentration of promoters on the catalytic performances of α-Al2O3 supported iron-cobalt bimetallic catalysts are investigated by using Ce, Ni, La, Ho, Ga Cu, Mn, and Zn used as promoters. A total of 49 catalysts were prepared by co-impregnation method and tested at 310 °C and 1 bar in a high-speed catalyst performance test system (HT-CPA). The FTS performances of catalysts showed that both the types and amounts of the promoters can affect light olefin production. The light olefin (C2=–C3=) production of unpromoted FeCo catalyst was about 3.87 × 10−3 (mol C/g active metal. h). The best performances were obtained from FeCo catalysts promoted with Ho, Cu, and Zn. Presence of these promoters increased olefin production up to ∼ 84 %, 76 % and 70 %, respectively.Performance parameters (MSE and R2) of RSM and ANN models revealed that both methods can be used to support experimental studies and provide a procedure for optimizing catalyst formulations yielding the desired product selectivity in FTS processes. The RSM outcomes aligned with experimental findings, suggest that that Ho, Cu, and Zn can serve as suitable promoters for the light olefin production in FTS. ANN model attained higher performance parameters (R2 = 0.95 and MSE = 2E−7) than RSM model (R2 = 0.85 and MSE = 3.4E−7). This indicates that ANN model, which designed as one hidden layer including 7 neurons, can provide better predictions and a fitting capacity. Therefore, it may be used in further optimization and sensitivity analysis approaches. Alignment degree between the experimental and modeling results demonstrates that the proposed methodology can provide a reliable and efficient way to guide experiments to optimize catalyst formulations through identification of potential promoters and their amounts to be used.

Study on a novel epoxy‐terminated dendritic modifier as an active toughening agent for epoxy resin

AbstractAlthough significant efforts have been undertaken to explore the toughening of epoxy resins, it remains challenges to establish a simple and effective toughening technique which does not compromise its strength, thermal stability and processing performance. In this paper, toluene‐diisocyanate‐trimer (TDI‐T) was utilized to manufacture a novel epoxy‐terminated dendritic modifier TDI‐T glycol diglycidyl ether (TDI‐T GLDE). When the addition of TDI‐T GLDE reaches 20% of the resin mass, the tensile strength, tensile elongation, compressive strength and impact strength were increased by 28.1%, 75%, 24.8%, and 138.0% respectively, compared to E‐51. The thermal properties of the samples have been improved, including an increased glass transition temperature (Tg) from 68.2 to 73.2°C, as well as an increase in the initial decomposition temperature from 240.6 to 257.7°C. The toughening mechanism of TDI‐T GLDE was studied through a combination of mechanical performance tests, thermal performance tests, and resin fracture surface morphology analysis.

A novel stereotyped phase change material with a low leakage rate for new energy storage building applications

Phase change materials (PCM) have been widely studied in the field of building energy storage. However, industrial grade high latent heat phase change paraffin (PW) has the problem of high melting point and easy leakage, and at the same time, it is necessary to absorb municipal solid waste on a large scale and reduce the damage of waste cellular concrete (WCC) to the urban ecological environment. Using binary paraffin wax (BP) prepared by hot fusion of solid paraffin (SP) and liquid paraffin (LP) as composite phase change materials, polypropylene (PP) and porous material WCC as support materials, a new WCC/PP/BP stereotyped phase change material (FCPCM) with low leakage rate and good stability was prepared by melt blending method and vacuum adsorption method, to meet the energy storage needs of buildings. The chemical compatibility, thermal performance and morphological stability of the prepared FCPCM were tested, and the heat storage/release performance test experiments were carried out to explore the thermal performance of the prepared energy storage concrete. The results show that the Encapsulated WCC/PP/BP has no new substance and good chemical compatibility. The results of scanning electron microscope (SEM) and mercury injection instrument (MIP) show that WCC has good adsorption properties for PP/BP. The melting phase change temperature increases by 14.08%, the latent heat of phase change decreases by 42.94%, and the initial phase change thermal properties are still maintained after several phases of phase change. It can maintain a stable form at 150℃. The 24 h leakage rate remained below 1%, which was nearly 44% lower than that of FCPCM with PP as the support material. Thermogravimetric curve (TGA) shows that the thermal stability of encapsulated FCPCM increases by 25.59%. In addition, the thermal performance test of energy storage concrete shows that compared with traditional concrete, energy storage concrete has greater heat storage density and stronger temperature control ability, which can effectively realize building energy saving.