Experimental Design Concepts Research Articles

Optimal experimental design on the loading frequency for a probabilistic fatigue model for plain and fibre-reinforced concrete

The objective is to improve the fatigue characterisation process based on the concept of optimal experimental design. This is carried out through a probabilistic model, previously developed, which takes into account the experimentally observed loading frequency effect on the fatigue life in plain and fibre-reinforced concrete. The Fisher Information Matrix is first obtained for the simplified fatigue model. The optimal design is found to be located at the minimum values allowed for both the maximum stress and stress ratio, whereas the two loading frequencies are the minimum and maximum values in the defined range. Next, the FIM is derived for the extended fatigue model. The previously carried out experimental plan is 65% efficient compared to the optimum. Even though it has been developed for the specific chosen fatigue model, the current procedure can be applied to any other fatigue model to significantly improve the fatigue characterisation process of any material.

An FEM-based approach for tool wear estimation in machining

This study presents an FEM-based approach to predict the rate of flank wear evolution for uncoated cemented carbide tools in longitudinal turning processes. This novel approach combines the concept of experimental design and Response Surface Methodology (RSM) with Finite Element (FE) modelling of the cutting process, which allows for a fairly accurate tool wear prediction with a significantly lower computational cost compared to other available numerical methods.In the current approach, a series of three dimensional (3D) FE simulations were initially performed for different combinations of cutting data and tool flank geometries. The obtained results were used to establish the quadratic relation between the input variables and the responses required for tool wear prediction, such as interface temperature. Later, the flank wear rate equation was developed based on the relation between the volume loss due to wear and the dimensions of the worn tools. The results of the FE simulations were finally integrated with the established wear rate equation to estimate the flank wear evolution. The credibility of the presented approach was then assessed through estimation of the flank wear evolution rate for a wide range of cutting conditions. The predicted flank wear rates showed a good agreement with experimental measurements in most cases. The reasons for minor deviations from the experimental results were finally outlined.

Developing an Empirical Relationship to Predict the Strength of Friction Stir Spot Welded Dissimilar Joints of Aluminum Alloy with Carbon Steel

The present investigation aims at developing an empirical relationship to predict the tensile shear strength of friction stir spot welded (FSSW) dissimiiar joints of (AA6061 aluminum alloy with carbon steel) incorporating parameters such as tool rotational speed, plunge rate, dwell time and tool diameter ratio. Experiments were conducted according to a four factor, five level central composite rotatable design of experiments concept. Strength of the joint was evaluated by a single lap shear test. Analysis of variance (ANOVA) technique was used to check the adequacy of the developed relationship. The developed empirical relationship can be effectively used to predict tensile shear strength of the joints at 95% confidence level.

Development of the Neuron Assessment for Measuring Biology Students’ Use of Experimental Design Concepts and Representations

Researchers, instructors, and funding bodies in biology education are unanimous about the importance of developing students' competence in experimental design. Despite this, only limited measures are available for assessing such competence development, especially in the areas of molecular and cellular biology. Also, existing assessments do not measure how well students use standard symbolism to visualize biological experiments. We propose an assessment-design process that 1) provides background knowledge and questions for developers of new "experimentation assessments," 2) elicits practices of representing experiments with conventional symbol systems, 3) determines how well the assessment reveals expert knowledge, and 4) determines how well the instrument exposes student knowledge and difficulties. To illustrate this process, we developed the Neuron Assessment and coded responses from a scientist and four undergraduate students using the Rubric for Experimental Design and the Concept-Reasoning Mode of representation (CRM) model. Some students demonstrated sound knowledge of concepts and representations. Other students demonstrated difficulty with depicting treatment and control group data or variability in experimental outcomes. Our process, which incorporates an authentic research situation that discriminates levels of visualization and experimentation abilities, shows potential for informing assessment design in other disciplines.

Progress and Challenges of Testing the Effectiveness of Stream Restoration in the Pacific Northwest Using Intensively Monitored Watersheds

Across the Pacific Northwest, at least 17 intensively monitored watershed projects have been implemented to test the effectiveness of a broad range of stream restoration actions for increasing the freshwater production of salmon and steelhead and to better understand fish–habitat relationships. We assess the scope and status of these projects and report on challenges implementing them. We suggest that all intensively monitored watersheds should contain key elements based on sound experimental design concepts and be implemented within an adaptive management framework to maximize learning. The most significant challenges reported by groups were (1) improving coordination between funders, restoration groups, and researchers so that restoration and monitoring actions occur based on the project design and (2) maintaining consistent funding to conduct annual monitoring and evaluation of data. However, we conclude that despite these challenges, the intensively monitored watershed approach is the most reliable means of assessing the efficacy of watershed‐scale restoration.

KONCEPCJA PROJEKTU STANOWISKA DO BADANIA ZJAWISK DYNAMICZNYCH ZACHODZĄCYCH PODCZAS UNOSZENIA ŁADUNKU

Summary. This article contains a description of an experimental design concept of test bench, which allows for a series of studies on the dynamic effects associated with lifting the load. Built on the basis of the proposed project test bench, allows for measurements such data as acceleration of the center of girder and the cargo, displacement of the cargo and the center of girder, measurement of stress in the selected locations on the structure, depending mainly on the specific construction of analyzed girder, dynamic surplus ratio and others. It is planned that an electrical and electronic part of test bench will be made with using a series of PHIDGET circuits, which are complete systems based on USB interface witch they are based on practically any programming language. Application of PHIDGET circuits allows mainly for full control of the system using a PC, and allows to immediate analysis of the data that are very important when the verification of the phenomenological

Optimization of fused deposition modeling process parameters: a review of current research and future prospects

Fused deposition modeling (FDM) is one of the most popular additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identification of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.

Determining high-quality critical body residues for multiple species and chemicals by applying improved experimental design and data interpretation concepts.

Ecotoxicological effect data are generally expressed as effective concentrations in the external exposure medium and do thus not account for differences in chemical uptake, bioavailability, and metabolism, which can introduce substantial data variation. The Critical Body Residue (CBR) concept provides clear advantages, because it links effects directly to the internal exposure. Using CBRs instead of external concentrations should therefore reduce variability. For compounds that act via narcosis even a constant CBR has been proposed. Despite the expected uniformity, CBR values for these compounds still show large variability, possibly due to biased and inconsistent experimental testing. In the present study we tested whether variation in CBR data can be substantially reduced when using an improved experimental design and avoiding confounding factors. The aim was to develop and apply a well-defined test protocol for accurately and precisely measuring CBR data, involving improved (passive) dosing, sampling, and processing of organisms. The chemicals 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 2,3,4-trichloroaniline, 2,3,5,6-tetrachloroaniline, 4-chloro-3-methylphenol, pentylbenzene, pyrene, and bromophos-methyl were tested on Lumbriculus variegatus (California blackworm), Hyalella azteca (scud), and Poecilia reticulata (guppy), which yielded a high-quality database of 348 individual CBR values. Medians of CBR values ranged from 2.1 to 16.1 mmol/kg wet weight (ww) within all combinations of chemicals and species, except for the insecticide bromophos-methyl, for which the median was 1.3 mmol/kg ww. The new database thus covers about one log unit, which is considerably less than in existing databases. Medians differed maximally by a factor of 8.4 between the 7 chemicals but within one species, and by a factor of 2.6 between the three species but for individual chemicals. Accounting for the chemicals' internal distribution to different partitioning domains and relating effects to estimated concentrations in the target compartment (i.e., membrane lipids) was expected to but did not decrease the overall variability, likely because the surrogate partition coefficients for membrane lipid, storage lipid, protein, and carbohydrate that were used as input parameters did not sufficiently represent the actual partitioning processes. The results of this study demonstrate that a well-designed test setup can produce CBR data that are highly uniform beyond chemical and biological diversity.

Using a discussion about scientific controversy to teach central concepts in experimental design

SummaryStudents may need explicit training in informal statistical reasoning in order to design experiments or use formal statistical tests effectively. By using scientific scandals and media misinterpretation, we can explore the need for good experimental design in an informal way. This article describes the use of a paper that reviews the measles mumps rubella vaccine and autism controversy in the UK to illustrate a number of threshold concepts underlying good study design and interpretation of scientific evidence. These include the necessity of sufficient sample size, representative and random sampling, appropriate controls and inferring causation.

Optimization of Cylindrical Grinding Process Parameters of OHNS Steel (AISI 0-1) Rounds Using Design of Experiments Concept

Optimization of Cylindrical Grinding Process Parameters of OHNS Steel (AISI 0-1) Rounds Using Design of Experiments Concept

A combination of Material Flow Cost Accounting and design of experiments techniques in an SME: the case of a wood products manufacturing company in northern Thailand

It is essential for small and medium-sized enterprises to manufacture products using standardized and sustainable methods. The case study company here is a wood products manufacturer, and an analysis of its production process revealed that almost 70% of the wood raw materials used is wasted in the form of chippings, sawdust, off-cuts and defects. The objective of this research study was therefore to apply the Material Flow Cost Accounting (MFCA) and Design of Experiments (DOE) concepts to the case study company, in order to reduce materials consumption and minimize waste. The research methodology was divided into two main parts. The first part employed the MFCA concept to analyze the inefficiencies incurred due to resource use within the production process, as well as the causes of such inefficiencies. In the second part, the opportunities available to reduce these inefficiencies were examined. The DOE concept was used to increase the efficiency of wood raw materials use, with a full factorial experiment used to find the optimal cutting settings, those creating less damage. Three factors were studied and an analysis of variance (ANOVA) was conducted. The results of the experiment have subsequently been put into practice, resulting in a reduction of wood materials losses in the cutting process, as a proportion of total wood materials used, from approximately 69 percent to 54 percent. In conclusion, applying MFCA and DOE helped both increase product quality and reduce the adverse environmental impacts of the case study company's production process, saving costs and improving its competitiveness.

Eating Up Experiments: Teaching Research Methods with Classroom Simulation and Food Detectives

Courses: A single-class activity for beginning communication research methods and research design coursesObjective: The concepts of experimental design, such as causality, confounding variables, time order, pretest and posttest designs, and so on, can be challenging to students and may seem abstract and daunting. Relating the concept to everyday, seemingly unrelated concepts and existing knowledge or schema through simulation, as well as with entertaining television programming, is one way to make research a more comfortable, approachable, and far less “stuffy” topic. This single-class activity attempts to illustrate this research design in an engaging manner.

Optimization of Carburized UNS G10170 Steel Process Parameters Using Taguchi Approach and Response Surface Model (RSM)

The utilization of carburizing materials in surface engineering has undergone many tremendous changes. Effective quality control is possible through carburizing the steel components under op-timal conditions. In this research work, process parameters like furnace temperature, soaking time and particle size of energizer were taken for optimization of carburized UNS-G10170 steel to yield maximum hardness using Taguchi’s design of experiment concepts and Response Surface Model. Nine experimental runs based on Taguchi’s L9 orthogonal array were performed; signal to noise (S/N) ratios, analysis of variance (ANOVA) and regression analysis were used with hardness as response variable. From the optimization and experimental analyses conducted, it was observed that furnace temperature, soaking time and particle size had significant influence in obtaining a better surface integrity. The optimal values obtained during the study optimization by Taguchi approach and Response Surface Model (RSM) were validated by confirmation experiments.

An experimental design approach for optimization of spectrophotometric method for estimation of cefixime trihydrate using ninhydrin as derivatizing reagent in bulk and pharmaceutical formulation

The aim of the present work is to use experimental design to screen and optimize experimental variables for developing a spectrophotometric method for determining cefixime trihydrate content using ninhydrin as a derivatizing reagent. The method is based on the reaction of the amino group of cefixime with ninhydrin in an alkaline medium to form a yellow-colored derivative (λmax 436nm). A two-level full factorial design was utilized to screen the effect of ninhydrin reagent concentration (X1), volume of ninhydrin reagent (X2), heating temperature (X3) and heating time (X4) on the formation of the cefixime–ninhydrin complex Y (absorbance). One way ANOVA and Pareto ranking analyses have shown that the ninhydrin reagent concentration (X1), volume of ninhydrin reagent (X2) and heating temperature (X3) were statistically significant factors (P<0.05) affecting the formation of the cefixime–ninhydrin complex Y (absorbance). A Box-Behnken experimental design with response surface methodology was then utilized to evaluate the main, interaction and quadratic effects of these three factors on the selected response. With the help of a response surface plot and contour plot the optimum values of the selected factors were determined and used for further experiments. These values were a ninhydrin reagent concentration (X1) of 0.2% w/v, volume of ninhydrin reagent (X2) of 1mL and heating temperature (X3) of 80°C. The proposed method was validated according to the ICH Q2 (R1) method validation guidelines. The results of the present study have clearly shown that an experimental design concept may be effectively applied to the optimization of a spectrophotometric method for estimating the cefixime trihydrate content in bulk and pharmaceutical formulation with the least number of experimental runs possible.

Inquiry-Based Active Learning: The Enhancement of Attitude and Understanding of the Concept of Experimental Design in Biostatics Course

The purpose of this study is to identify the effect of using active inquiry-based learning in conducting experiment in the subject of Biostatic. The experiment included 1) Instructional Re-designation, 2) planning of the active learning process, and 3) application of the inquiry-based active learning. The sample involved 96 trainee teacher enrolled in biology program in the university of Riau, Indonesia, as respondents, and they were divided into two groups 48 respondents for year 2011 and 48 respondents for year 2012. To collect data, questionnaire, focusing on attitude from peers’ perspectives, whereas the test was given to identify students’ level of understanding the content of biology were employed. As the students were given test after finishing each chapter they learnt. The finding shows that attitude of the students changed after using the inquiry-based learning. In addition, the finding shows that as a result of using inquiry-based learning, achievement of the majority of the students from two groups in 2011 and 2012 was at good level. This means that the inquiry-based learning can be used as one of the method to increase students’ achievement and change their style of learning especially in conducting experiment in science subject.

Editorial/Letters/Crossword

Editorial/Letters/Crossword

Turning Investigations on Machining of Ti64 Alloy with Different Cutting Tool Inserts

Turning operation is fundamental in the manufacturing industry to produce cylindrical parts especially for producing near-nett shape, and aesthetic requirements with good dimensional accuracy. This present research chapter, an attempt has been made to investigate the machining characteristics of titanium alloys. The investigation has been carried out to measure the effect of tool flank wear, surface roughness, cutting force and temperature on different cutting tools by adopting Taguchi’s design of experiment concept. This investigation was set to analyse and develop a mathematical model using response surface methodology, fuzzy logic. The observed responses were optimized using grey relational grade algorithm. Except for a few cases, the experimental results have close proximity (95%) to the predicted value. This validates the model developed in this work. Orthogonal array with grey relational analysis has been successfully implemented for the optimization of the machining parameters. The optimized cutting conditions evolved in this research study will help to achieve better machinability of these advanced materials like titanium alloy.

O tempo de pega em gelatinas comerciais: uma experiência da disciplina de quimiometria para estudantes de graduação em Química

The aim of this paper is to describe a chemometrics experiment for undergraduate chemistry students using basic concepts of experimental design to determine setting-time of commercial gelatins.

Application of the central composite design in optimization of machining parameters in drilling hybrid metal matrix composites

In this study, the application of response surface methodology (RSM) and central composite design (CCD) for modeling, optimization, and an analysis of the influences of dominant machining parameters on thrust force, surface roughness and burr height in the drilling of hybrid metal matrix composites produced through stir casting route. Experiments are carried out using Al 356-aluminum alloy reinforced with silicon carbide of size 25μm and Mica of size 45μm. Drilling test is carried out using carbide drill of 6mm diameter. The design of experiment concept has been used to optimize the experimental conditions. The experimental data are collected based on a three-factor-three-level full central composite design. The multiple regression analysis using RSM is used to establish the input–output relationships of the process. The mathematical models are developed and tested for adequacy using analysis of variance and other adequacy measures using the developed models. The main and interaction effect of the input variables on the predicted responses are investigated. The predicted values and measured values are fairly close, which indicate that the developed models can be effectively used to predict the responses in the drilling of hybrid metal matrix composites. The optimized drilling process parameters have been obtained by numerical optimization using RSM by ensuring the minimum thrust force of 84N, surface roughness of 1.67μm, and the burr height of 0.16mm. After the drilling experiments, a scanning electron microscope (SEM) is used to investigate the machined surface and tool wear.

Statistical methods for quantitative mass spectrometry proteomic experiments with labeling

Mass Spectrometry utilizing labeling allows multiple specimens to be subjected to mass spectrometry simultaneously. As a result, between-experiment variability is reduced. Here we describe use of fundamental concepts of statistical experimental design in the labeling framework in order to minimize variability and avoid biases. We demonstrate how to export data in the format that is most efficient for statistical analysis. We demonstrate how to assess the need for normalization, perform normalization, and check whether it worked. We describe how to build a model explaining the observed values and test for differential protein abundance along with descriptive statistics and measures of reliability of the findings. Concepts are illustrated through the use of three case studies utilizing the iTRAQ 4-plex labeling protocol.