Statistical Experimental Method Research Articles

Personalizing the learning process through data mining in higher education

Relevance. The rapid evolution of the modern labor market necessitates a shift from traditional, standardized career counseling to personalized educational trajectories that account for individual qualities, skills, and preferences, ensuring better professional adaptability and satisfaction. Purpose. The purpose of the study is to develop and validate a model that will facilitate the selection of a person-centred educational and professional pathway for students. Methodology. The research methods are comparative, qualitative, and statistical analysis, experimental method, modelling, and prototyping. Results. The main result of the study was the creation and successful application of an original learning model integrated with modern analytical approaches, including predictive analysis mechanisms for adapting and optimizing individual educational trajectories, which significantly improved the efficiency of the learning process. Experimental implementation showed that students who used the developed model to create their individual educational trajectories achieved a significant improvement in their academic performance and motivation to learn compared to the control group. The hypothesis that personalized guidance influences the choice of more appropriate curricula and courses was confirmed, which in turn has a positive effect on academic performance and satisfaction with learning. The presence of positive feedback from students and teachers also indicates the high adaptability of the model and its potential for scaling up and further implementation in educational practice. Conclusions. The study validated the positive impact of a personalized approach on students' academic motivation and performance, revealing significant advantages in engagement, strategic career planning, and long-term purposefulness, while also highlighting the need for further research to scale the model, optimize prediction algorithms, and adapt the approach to diverse learning environments and educational standards. Keywords: adaptive education; statistical modelling; educational modelling; learning technologies; educational motivation; forecasting methodologies; qualification development

A Taguchi approach to the influence of infiltration parameters on microstructure and properties of W–ZrC composites prepared by the displacive compensation of porosity (DCP) method

In the present work, tungsten carbide (WC) preforms were fabricated by gel-casting process using nontoxic Na-alginate and then reactively infiltrated by molten Zr2Cu to produce W-ZrC composite via displacive compensation of porosity process. An orthogonal array design (OAD) was employed as a statistical experimental method for the fabrication of W-ZrC composites. This paper deals with the analysis of the infiltration parameters such as temperature and time on the microstructures and properties of W-ZrC composites based on Taguchi's experimental design methods. The results of ANOVA showed that infiltration temperature as the most consequential factor affecting the amount of ZrC phase, flexural strength and Vickers hardness. The optimized sample had a flexural strength of 460 ± 4 MPa, Vickers hardness of 9.5 ± 0.4 GPa, relative density of 95.21 ± 1.07 and deflection at the fracture point of 0.19 ± 0.04 mm.

Optimization of Hydrothermal Temperature and Time Parameters in the Synthesis of Hierarchical ZSM-5 from Kaolin by Taguchi Method

Hierarchical ZSM-5 was successfully synthesized by hydrothermal crystallization of kaolin clay. A statistical experimental design Taguchi method with analysis of variance (ANOVA) with an L9 Orthogonal array (OA) was used to optimize the formation of high mesoporosity in hierarchical ZSM-5. Samples from kaolin mixtures crystallized at 80-175°C for 12, 24 and 48 h, respectively using hydrothermal followed by addition of mesoporogen cetyltrimethylammonium bromide (CTABr) surfactant. The presence of pentasil zeolite groups and large mesopores surface area and pore volume has observed on the samples by FTIR and N2 adsorption-desorption technique.The optimum synthesis conditions studied by Taguchi analysis based on S/N ratio for temperature and time of hydrothermal. The optimum condition was 127.5°C and 48 h giving the highest mesoporosity. Data analysis of interaction plot for S/N ratio showed there was interaction between temperature and time in the crystallization of hierarchical ZSM-5. Hydrothermal temperature was the most influencing factors for the formation of hierarchical ZSM-5 with a percent contribution of 83%.

Experimental Study on Breakdown Time Delay of Hundreds of Nanoseconds Pulse Under Different du/dt for mm Gaps

The characteristics, breakdown probability, and statistical distribution of breakdown time delay under different du/dt in hundreds of nanoseconds pulse for millimeter gaps have been investigated by employing the statistical experimental method in this paper. The experimental results indicate that both the breakdown time delay and jitter are essentially decreased as the slope of the pulse voltage- du/dt is increased for 1-, 2-, and 4-mm gaps; in particular, increasing the value of du/dt is useful to obtain the smaller relative deviation of breakdown time delay under the same breakdown electric field. The breakdown probabilities for different gaps have been analyzed and a method of utilizing the Gaussian distribution function has been proposed which can be used for evaluating the statistical distribution of breakdown time delay. When the experimental condition is 100% breakdown probability, the breakdown time delay follows a Gaussian distribution. However, it is unsuitable for the fitting of breakdown time delay utilizing a Gaussian function for 2- and 4-mm gaps from the cumulative probability distributions of breakdown time delay because of the lower du/dt values and breakdown probabilities.

Analysis and comparison of some criteria of checking the probability distribution deviation from the normal distribution law

A number of criteria of sample data concordance with the normal probability distribution law has been classified, and some recommendations for using these criteria in practice of engineering statistical analysis have been given. An original approach to testing the considered criteria has been proposed, which is based on the logics of building significance criteria, which allowed placlacing the criteria in the order of preference, when the standard normal distribution is taken for reference. This approach has been tested earlier in assessing adequacy of statistical mathematical models and assessing the degree of statistical similarity, when the information about performance quality of complex technical systems is combined, which was obtained in the process of experimental development. However, applying this approach to the problems of comparing criteria of measurement data concordance with the normal probabilities distribution law required additional research caused by lack of programs and tables of percentage points normality criteria statistics. The article presents the results of using of the interval estimation and experimental-statistical method of Taguchi for solving the problem.

PRECISION, STABILITY ANALYSIS OF THE CRANKSHAFT GRINDING TECHNOLOGICAL PROCESS

Introduction. The article is devoted to the problem of the crankshafts quality of automotive tractor engines on the example of YaMZ - 238NB engines. Despite years of experience in the repair industry to implement the technological process of the crankshafts grinding during their restoration, the quality of its implementation is not sufficient. Therefore, for reducing errors in restoring crankshafts, as well as in any other parts, it is possible only if the reasons for their occurrence are promptly identified. The purpose of the research is to identify the reasons of the errors in the process of grinding crankshafts for repair dimensions according to the results of technical control and observation of the technological process.Materials and methods. The methodological basis for experimental and theoretical research is a system analysis. The structural and functional representation of the object is also used for research, and the model for the analysis of the grinding process serves as the basis for the decomposition.Results. While analyzing the measurements results of the rod necks connection and polishing for repair dimensions, the transformed experimental-statistical method is applied. The peculiarity of the method consists in the algebraic transformation of the calculation algorithm, which is reduced to simple formulas for semi-finished products and which makes it easy to program calculations on the computer. In addition, the order of processing the number of obtained numerical values and construction of distribution curves is stated for estimating the correspondence between the probability of the experimental distribution and the theoretical distribution.Discussion and conclusions. The implementation of the algorithm for calculating the accuracy and stability for the technological process of grinding the crankshafts during their restoration would reduce the error value. Moreover, the reduction of errors during the process of crankshafts restoration would improve the quality of repair, thus prolonging the crankshaft serviceability.

ЕКСПЕРИМЕНТАЛЬНО-СТАТИСТИЧНИЙ МЕТОД ОБЧИСЛЕННЯ КОРЕЛЯЦІЙНОЇ ВЗАЄМОЗАЛЕЖНОСТІ ПАРАМЕТРІВ РОЗПІЗНАВАННЯ ЗАСОБІВ НЕГЛАСНОГО ОТРИМАННЯ ІНФОРМАЦІЇ

ЕКСПЕРИМЕНТАЛЬНО-СТАТИСТИЧНИЙ МЕТОД ОБЧИСЛЕННЯ КОРЕЛЯЦІЙНОЇ ВЗАЄМОЗАЛЕЖНОСТІ ПАРАМЕТРІВ РОЗПІЗНАВАННЯ ЗАСОБІВ НЕГЛАСНОГО ОТРИМАННЯ ІНФОРМАЦІЇ

Development of a method for the experimental estimation of multimedia data flow rate in a computer network

We have developed a method for the experimental estimation of rate of multimedia data stream in a computer network based on the methods of mathematical statistics. The method, in contrast to the existing ones, is based on considering the rate of multimedia data stream as a random variable that obeys the normal distribution law. When designing computer networks, in order to estimate the required throughput, mathematical streaming traffic models are applied. Such an approach is justified when the constraints of mathematical models are met, such as stationarity, ordinarity, and the absence of aftereffect for the Poisson stream of packets. Under actual conditions, estimates for characteristics of data flow, derived using existing models, may prove to be too conservative as a result of failure to comply with conditions of stationarity of the packet stream. An alternative way for solving a given task is the development of a statistical experimental method for estimating the rate of multimedia data stream in a computer network. The proposed method makes it possible to derive the values of mathematical expectation and a standard deviation in data transmission rate, as well as to estimate consistency of the hypothesis about a normal character of the distribution law of multimedia data flow rate. The experimental estimates are given for the multimedia data stream rate in a computer network at different values of resolution and frame rate of the video. These results showed that the experimental estimates exceed analytical data by 3...20 %. The values of multimedia data flow rate estimates, acquired using the proposed method, could be used to estimate the load of segments in the designed computer network, as well as to explore the throughput of segments in the existing computer network.

A novel dielectrophoresis potential spectroscopy for colloidal nanoparticles.

Dielectrophoresis (DEP) has been widely used to manipulate nanoparticles in microfluidic applications. However, determination of the DEP force of nanoparticles by theoretical models is not easy due to complications caused by the polarization of electrical double layer. Additionally, there is a lack of suitable experimental techniques to quantify the DEP force of nanoparticles. This article reports a statistical mechanics-based experimental method to determine the DEP potential energy of a single particle by measuring the equilibrium number density of particles in a DEP force field. Results show that at high frequencies, the measured potentials agree with the Maxwell-Wagner-O'Konski (MWO) theory. At frequencies lower than the crossover frequency (ωco ), the measured potential values are larger than MWO theory's predictions. When an effective particle radius (particle radius plus Debye length) is used to replace the particle radius, MWO theory fits better with the measured potentials on both sides of ωco . Also, the measured ωco was found inversely proportional to the effective particle radius, which agrees with MWO theory. The new DEP potential spectroscopy is not limited to the size or shape of particles, opening doors to investigate the DEP response functions of quantum dots and proteins in an alternating current electric field.

Usage of Iranian scoria for copper and cadmium removal from aqueous solutions

The competitive removal of copper and cadmium from aqueous solutions using scoria has been investigated. Scoria was characterized by various methods, such as XRD, XRF, FT-IR and SEM. The results show that scoria sample contained augite, enstatite, diopside, and olivine. These minerals were separated from each other and each mineral was then subjected to the adsorption experiments. It was found that the main absorbent constituent in scoria was augite. Finally, statistical experimental method was used to optimization of adsorption conditions (Initial concentration of copper and cadmium ions, the amount of scoria and temperature) for removal of Cu (II) and Cd (II) ions from solution in optimum conditions. The optimum conditions are obtained as follows: concentrations of Cu (II) and Cd (II) of 400×10−6 and 554×10−6, respectively; amount of scoria of 7 g; temperature of 38 °C. Under these conditions Cu (II) and Cd (II) ions are absorbed onto the scoria more than 79% and 16%, respectively.

Preparation of ACE Inhibitory Peptides fromMytilus coruscusHydrolysate Using Uniform Design

The angiotensin-I-converting enzyme (ACE) inhibitory peptides from mussel, Mytilus coruscus, were investigated and the variable factors, protease concentration, hydrolysis time, pH, and temperature, were optimized using Uniform Design, a new statistical experimental method. The results proved that the hydrolysate of alkali proteases had high ACE-inhibitory activity, especially the alkali protease E1. Optimization by Uniform Design showed that the best hydrolysis conditions for preparation of ACE-inhibitory peptides from Mytilus coruscus were protease concentration of 36.0 U/mL, hydrolysis time of 2.7 hours, pH 8.2, and Temperature at 59.5°C, respectively. The verification experiments under optimum conditions showed that the ACE-inhibitory activity (91.3%) were agreed closely with the predicted activity of 90.7%. The amino acid composition analysis of Mytilus coruscus ACE-inhibitory peptides proved that it had high percent of lysine, leucine, glycine, aspartic acid, and glutamic acid.

THE INFLUENCES OF NATURAL GAS IMPURITIES TO THE SURFACE TENSION OF BLENDED PIPERAZINE-N-METHYLDIETHANOLAMINE (MDEA) SOLUTION

This study focuses on the effect of impurities in the natural gas stream on the characteristic of surface tension in the blended piperazine and MDEA solution. Hydrocarbon liquids, Iron Sulphide, Sodium Chloride, Acetic Acid, Methanol and Polyethylene Glycol were used as the impurities. The results indicated that the type of impurities determined the surface tension changes of the amine solution. The concentration of piperazine-MDEA blends also enhanced to the increasing of surface tension. Iron sulphide, hydrocarbons and sodium chloride as the impurities in the amine solution were the most influential factors to the surface tension. Statistical experimental method was employed to determine the main effect in the increasing of surface tension. Full factorial design and response surface methodology (RSM) coupled with central composite design (CCD) were used to determine the increasing of surface tension in the amine solution. A central composite design was used to determine the main variables such as iron sulphide, hydrocarbon and sodium chloride. The maximum surface tension of 74.33 mNm-1 was determined at the combined impurities concentrations of Iron Sulphide at 6.346 ppm, Hydrocarbon liquids at 11.827 ppm and Sodium Chloride at 8.261 ppm.Pada penelitian ini difokuskan untuk mengetahui pengaruh impuritas didalam aliran gas alam terhadap karakteristik tegangan permukaannya pada campuran larutan MDEA-piperazin. Hidrokarbon, besi sulfida, NaCl, asam asetat, methanol dan PEG digunakan sebagai larutan impuritas pada gas alam. Pada penelitian ini menunjukan bahwa jenis dari impuritas akan mempengaruhi besarnya tegangan permukaan yang dihasilkan pada larutan amin. Konsentrasi larutan amin juga mempengaruhi tegangan permukaan yang dihasilkan. Besi sulfida, hidrokarbon dan NaCl adalah faktor penting yang menentukan besanya tegangan permukaan yang dihasilkan. Metode statistik yang menggunakan response surface methodology (RSM) yang digabungkan dengan central composite design (CCD) telah digunakan untuk mengetahui faktor utama yang menentukan tegangan permukaan. Tegangan permukaan yang paling tinggi dihasilkan pada konsentrasi besi sulfida 6,346 ppm, hidrokarbon 11,827 ppm dan NaCl 8,261 ppm adalah sebesar 74,33 mNm-1.

Applying the statistical experimental method to evaluate the process conditions of TiO 2 nanotube arrays by anodization method

Vertically oriented TiO 2 nanotube arrays were successfully produced by the anodization technique in NH 4F/H 3PO 4 electrolyte. The structure and morphology were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). It is found that TiO 2 nanotube arrays annealed at 500 °C containing 100% anatase phase and entirely converted into rutile at 800 °C. The response surface methodology (RSM) and Box-Behnken design were applied to find the optimal factor conditions in production of TiO 2 nanotube arrays. Based on the results in preliminary experiments, we selected anodization time, anodization voltage and NH 4F concentration as the key factors to investigate their effects on responses. The regression models were built by fitting the experimental results with a second-order polynomial. By using the regression models, the optimal factor conditions were obtained as follows: anodization time of 300 min; anodization voltage of 15.39 V; NH 4F concentration of 0.50 M. Corresponding to the optimal factor conditions, the predicted average length and diameter of nanotube array were 1429 nm and 33 nm, respectively. Confirmation experiments using the optimized conditions were performed: TiO 2 nanotube arrays were obtained with an average tube length of 1420 nm and average tube diameter of 36 nm. The experimental results are in good agreement with the predicted results.

Orthogonal array design method for optimization experiments of sodium azide microencapsulation with stearic acid

In this study, an orthogonal array design (OAD), OA 9, was employed as a statistical experimental method for mircoencapsulation of sodium azide with stearic acid through a solvent/non-solvent procedure which is based on the coacervation principle. Scanning electron microscopy (SEM) was used to examine the coating morphology. The effect of stearic acid coating on sodium azide decomposition has been studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC). Our findings revealed that stearic acid can provide an effective coating shell around sodium azide microparticle and the coating quality is affected by some parameters, such as percent of stabilizer, addition time of non-solvent, volume of non-solvent and stirring speed of the mixture (revolutions per minute, rpm). The effects of these factors on the thermal decomposition temperature of microencapsulated sample were quantitatively evaluated by the analysis of variance (ANOVA). The statistical results showed that sodium azide powder can optimally be coated and stabilized by controlling of stabilizer percent, addition time of non-solvent, and volume of non-solvent. The OAD evaluation of initial experimental data provide optimized amount of the parameters to obtain the most stabilized sample, at which the thermal decomposition temperature of sodium azide is predicted at 436 °C. The prediction is in excellent agreement with experimental result obtained at the same conditions that is 435 °C. These data could be compared to that of the pure stearic acid and sodium azide in which decomposition temperature ranges are 160–300 and 382–397 °C, respectively. Also, the kinetic parameters such as activation energy and frequency factor of the decomposition processes of pure components and microencapsulated sodium azide at optimum condition were obtained from the DSC data by non-isothermal methods proposed by ASTM E696. Our finding showed that the treated NaN 3 has much lower decomposition rate as compared to the pure one.

Determination of the Optimal Conditions for Synthesis of Silver Oxalate Nanorods

AbstractIn this study, an orthogonal array design (OAD), OA9, was employed as a statistical experimental method for the controllable, simple and fast synthesis of silver oxalate nanorods. Ultrafine silver oxalate rods were synthesized by a precipitation method involving the addition of silver ion solution to the oxalate reagent. The effects of reaction conditions, i.e., silver and oxalate concentrations, flow rate of reagent addition and temperature, on the diameter of the synthesized silver oxalate rods were investigated. The effects of these factors on the width of the silver oxalate rods were quantitatively evaluated by the analysis of variance (ANOVA). The results showed that silver oxalate nanorods can be synthesized by controlling the silver concentration, flow rate and temperature. Finally, the optimum conditions for the synthesis of silver oxalate nanorods by this simple and fast method were proposed. The results of ANOVA showed that 0.001 mol/L silver ion concentration, 40 mL/min flow rate for the addition of the silver reagent to the oxalate solution and 0 °C temperature are the optimum conditions for producing silver oxalate nanorods with 107 ± 45 nm width.

Saturated Fractional Design of Experiments: Toughness and Graphite Phase Optimizing in Nihard Cast Irons

The aim of the present research is to identify the manufacturing factors that exert an active influence on the graphite phase formation in mottled Nihard cast irons constituting the roll shells of duplex work rolls processed by the double pour method during centrifugal casting. The studied rolls, referred to as alloy indefinite chill, were processed at industrial scale and had a core consisting of spheroidal graphite cast iron with a matrix of ferrite and pearlite. An additional aim of this study was to evaluate the effect and extent of these factors on the dynamic toughness response of the roll shell material.The research methodology employed consisted of the application of a saturated design of experiments with seven factors, eight experiments, and resolution III. The measured responses for graphite were: the volume fraction, count number per unit area, and morphology, determined by quantitative metallography. Impact testing was characterized by Charpy tests on U-notched specimens at 350 °C. The manufacturing factors studied were: the final weight percent of silicon, sulfur, and manganese; the liquidus and the casting temperatures; and, finally, inoculation with SiCaMn and A-type FeSi (with Zr).The statistical experimental method conducted allowed us to confirm the significance of factors such as the %Si, the liquidus temperature and inoculation with SiCaMn on the precipitation of graphite in a white cast iron such as the Nihard irons used in the roll shell, in agreement with the precipitation of graphite in gray cast irons widely reported in the literature. It was also shown that the development of lamellar graphite shapes were favored by an increase in the total equivalent carbon and also by the increase in the amount of A-type FeSi added. Furthermore, the impact toughness was shown to improve with the increase in both the %Si and the liquidus temperature.

Tolerância de leguminosas de cobertura do solo a Herbicidas

São poucas as pesquisas de tolerância de leguminosas de cobertura do solo a herbicidas visando selecionar produtos que sejam seletivos a estas plantas e que apresentem controle satisfatório das plantas daninhas. Com o objetivo avaliar a tolerância de quatro leguminosas a herbicidas, instalou-se um experimento em condições de casa-de-vegetação. As leguminosas foram plantadas em sacos plásticos de dois litros, contendo substrato homogeneizado com duas sementes das leguminosas Pueraria phaseoloides, Desmodium ovalifolium, Mucuna aterrima e Mucuna cochinchinensis. Os herbicidas aplicados foram 2,4-DB, em pós-emergência, e alachlor, imazaquin e pendimethalin em pré-emergência. O delineamento experimental foi inteiramente ao acaso, em esquema fatorial de 4x4x5x4 com quatro espécies de leguminosas, quatro herbicidas e cinco doses de cada herbicida, respectivamente, repetidos quatro vezes. Aos trinta e seis dias após o plantio a Pueraria phaseoloides mostrou-se tolerante aos herbicidas alachlor e imazaquin e suscetível ao 2,4-DB e pendimethalin. O Desmodium ovalifolium foi suscetível aos herbicidas nas doses usadas, exceto o alachlor. A Mucuna aterrima apresentou tolerância ao alachlor, imazaquin e pendimethalin e foi suscetível ao 2,4-DB. Os herbicidas alachlor e imazaquin não foram fítotóxicos à Mucuna cochinchinensis, enquanto 2,4-DB e pendimethalin causaram severas injúrias.

Preparation of silica nanoparticles: determination of the optimal synthesis conditions for small and uniform particles

Silica nanoparticles were prepared from tetraethylortho-silicate (TEOS) dissolved in ethanol by using a semi-batch process in order to control the particle properties. In this work, the statistical experimental method was also used to compare the properties (particle size and SD) of the SiO 2 particles according to the four parameters ( R=[H 2O]/[TEOS]), concentration of ammonia (NH 3), the feed rate of reactant, reaction temperature]. We have obtained monodispersed silica particles having size ranging from 10 to 350 nm by our experiment. It was found that the optimal synthesis conditions for the preparation of SiO 2 nanoparticles with narrow size distribution in semi-batch process were as follows; ( R=[H 2O]/[TEOS], 30–55; concentration of ammonia (NH 3), 0.2–0.35 mole l −1; feed rate of reactant, 13–17 cm 3 min −1; reaction temperature, 55–65°C). The above-mentioned optimal conditions were used to prepare the particles with minimum particle size (30 nm) and its SD (<±5 nm), simultaneously. Experimental results measured by using the optimal synthesis conditions were in a good agreement with simulated value and the smallest size (∼10 nm in diameter) was obtained. Also, we found that the effect of parameters on the particle size and SD in the preparation of SiO 2 nanoparticles was increased in the following order; reaction temperature, ( R=[H 2O]/[TEOS]); concentration of ammonia (NH 3), feed rate of reactant.

Synthesis of TiO 2 nanoparticles by hydrolysis of TEOT and decrease of particle size using a two-stage mixed method

A new preparation method of particles was introduced, which consisted of a semibatch–batch two-stage reaction to decrease the size of TiO 2 fine particles. Using a semibatch process as a first stage, the particle size grew to a certain level (132 nm). Using a batch process as a second stage, however, the particle size decreased about 42 nm. The particles prepared by using a two-stage (semibatch–batch) method had a smaller mean particle size and smaller standard deviation than those obtained from the single-stage process. In this work, the statistical experimental method was also used to compare the various properties of the TiO 2 particles according to the six parameters [concentration of TEOT during 1st and 2nd stages, reaction temperature during 1st and 2nd stages, the amount of hydroxypropyl cellulose (HPC) during 1st and 2nd stages]. It was found that the optimum conditions for the maximum reduction of TiO 2 particle size using this method were as follows: (1st TEOT (M): 0.091, 2nd TEOT (M): 0.146, 1st temperature (°C): 20.0, 2nd temperature (°C): 38.2, 1st HPC (×10 −2 g/cm 3): 0.018, 2nd HPC (×10 −2 g/cm 3): 0.290). The experimental results measured by using the above optimum conditions were in agreement with calculated results and produced the smallest size (∼42 nm in diameter) with the value of DPS (−90 nm). In addition, we found that the main parameters affecting the decrease of particle size were concentration of TEOT and the reaction temperature during second stage.

Etching of aluminum alloys in the transformer-coupled plasma etcher

Transformer-coupled plasma (TCP) technology has been applied to the etching of aluminum alloys. High density plasmas can be obtained at low pressures (∼10 mTorr) by inductive coupling of externally applied radio frequency (rf) power at the frequency of 13.56 MHz. The energy of the ions incident to the substrate is controlled by a separate capacitively coupled rf power supply. Cl2 and BCl3 gas chemistries were used for the etching. The characteristics of the plasma have been studied with a Langmuir probe and the ‘‘complex conjugate method.’’ The ion current density is mainly dependent on the rf power to the coil and gas pressure. The energy of ions bombarding the substrate surface can be controlled by changing the rf power to the bottom electrode and the coil. A statistical experimental method and optical emission spectroscopy were used to study the etching of the aluminum alloys with a TCP source. The results indicate that etching of aluminum alloys is dominated by chemical interaction with Cl2 gas whereas photoresist is etched by the bombardment of energetic ions.