Dimensional Analysis Method Research Articles

Evaluation of experimental testing methods for the design of permeable friction course mixtures

Since the first mix design of the permeable friction course (PFC), there are currently more than 20 methods used to design PFC mixtures, and thus it is important to evaluate these methods for optimum design. This paper compares the differences of several critical procedures specified in the main design methods of PFCs and their effects on performances, specifically the procedures of specimen compaction (Marshall compaction and Superpave Gyratory Compaction), the draindown test (beaker method, test pan method, and wire basket method), the theoretical maximum specific gravity assessment (vacuum saturation, solvent immersion, and asphalt immersion), and the bulk specific gravity assessment (dimension analysis and corelok method). The effects of different types of aggregates and test methods on properties of PFC mixes were investigated, and it was found that the testing results acquired by different test methods were clearly different. The wire basket, asphalt immersion, and corelok methods all showed better performances for PFC mixes than the others.

Three-point bending of thin-walled rectangular section tubes with indentation mode

The local indentation and bending collapse are two typical energy dissipation mechanisms of thin-walled tubes under lateral impacts. These two mechanisms are always developed simultaneously for tubes under three-point bending, but there are still few studies concerned with this phenomenon. This paper addresses the indentation mode of thin-walled tubes under three-point bending. Quasi-static experimental tests are conducted first for square tubes with particular dimensions, and the nonlinear finite element code LS-DYNA is then used to simulate the tests. Parametrical studies are conducted to analyze the influence of geometrical parameters on deformed shapes and force response. Results show that the span, wall thickness and punch diameter have significant influence on the response of tubes, while the sectional width has a small influence. On the basis of the analysis of energy dissipation mechanisms, a theoretical model is proposed to predict the force response of thin-walled tubes. Ideal rigid perfectly-plastic material assumption and the dimensional analysis method are employed to help derive the force-displacement characteristics. Finally, the theoretical predictions are validated by experiments and simulation results of thin-walled rectangular tubes with a wide range of geometric parameters.

Development of semi empirical model on material removal rate in WEDM process for aluminium metal matrix material using dimensional analysis

Wire electrical discharge machining is a non-conventional process for manufacturing complicated and intricate parts. In this paper, dimensional analysis and nonlinear estimation method Quassi Newton was used to established semi empirical model for various aluminium metal matrix material considering pulse on time, wire diameter, peak current and various materials properties likes density, thermal conductivity, electrical conductivity, specific heat capacity, coefficient of thermal expansion, melting temperature, and latent heat of fusion as model parameter. Taguchi L27 orthogonal array were used to perform the experiment for aluminium metal matrix. Semi empirical model shows more than 99% prediction than experiment data. Constant and power indices value of model shows wire diameter, peak current, pulse on time and work material properties such as thermal expansion of coefficient and melting point temperature are significant parameters for material removal rate. [Submitted 26 August 2017; Accepted 2 April 2018]

Development of semi empirical model on material removal rate in WEDM process for aluminum metal matrix material using dimensional analysis

Wire electrical discharge machining is a non-conventional process for manufacturing complicated and intricate parts. In this paper, dimensional analysis and nonlinear estimation method Quassi Newton was used to established semi empirical model for various aluminium metal matrix material considering pulse on time, wire diameter, peak current and various materials properties likes density, thermal conductivity, electrical conductivity, specific heat capacity, coefficient of thermal expansion, melting temperature, and latent heat of fusion as model parameter. Taguchi L27 orthogonal array were used to perform the experiment for aluminium metal matrix. Semi empirical model shows more than 99% prediction than experiment data. Constant and power indices value of model shows wire diameter, peak current, pulse on time and work material properties such as thermal expansion of coefficient and melting point temperature are significant parameters for material removal rate. [Submitted 26 August 2017; Accepted 2 April 2018]

Simultaneous determination of gas leakage location and leakage rate based on local temperature gradient

In this study, a quantitative non-contact detection method for gas leakage problem based on infrared thermography technology is developed. First, the relationship between the gas leakage rate and the temperature gradient at the edge of the leaking hole is established based on thermodynamics, dimensional analysis and numerical methods. Second, the temperature fields surrounding the gas leakage location are extracted using an infrared thermal imager. Both the gas leakage location and leakage rate are obtained for the damaged rubber seals. Finally, the detections of gas leakage location with arbitrary shape and no obvious temperature difference are discussed and generalized. These results will play an important role in detecting the leakage rate for the damaged seal structures or containers.

Strengthening Community: Older Asian Immigrants' Contributions to New Zealand Society.

This study sought to uncover the process through which older Chinese, Indian and Korean immigrants residing in Auckland, New Zealand contribute to, and participate in, local community. There is a paucity of literature addressing the everyday activities of older Asian immigrants living in New Zealand. The few studies that do exist focus solely on one ethnic group with little discussion of how community participation occurs. Grounded theory methodology was employed. Focus groups and individual interviews with 76 Chinese, Indian or Korean older immigrants were recorded, transcribed, translated, and analysed using grounded theory methods of dimensional analysis to develop a theory of participation. Older Asian immigrants contribute to society through a process of Strengthening Community; comprising three perspectives: Advancing Cultural Connectedness, Giving Service and Caring for Family. Each perspective is mediated by conditions and strategies that facilitate when and how participants engage in their chosen activities. Older Asian immigrants are active social contributors to New Zealand communities. Although they encounter barriers to participation, they constantly seek ways to work individually and in community groups to effectively contribute to civic society. In doing so, they take pride in giving back to their host country.

Analysis of alkaloids from Peganum harmala L. sequential extracts by liquid chromatography coupled to ion mobility spectrometry

An orthogonal two dimensional analysis method based on high performance liquid chromatography (HPLC) separation and electrospray ionization-ion mobility spectrometry (ESI-IMS) detection was developed for the analysis of alkaloid compounds from Peganum harmala L. seeds. Reverse phase (RP) and hydrophilic interaction chromatography (HILIC) were compared for the most optimal performance using three different chromatographic columns. The experimental results suggest that HILIC mode is a better option for combining with the ESI-IMS system for higher sensitivity and ease in hyphenating. Under optimized conditions, alkaloids from different extraction phases were determined by means of the established HPLC-IMS method. More compounds from Peganum harmala L. seed extracts were differentiated on the HPLC-ESI-IMS system by their retention time and drift time than by HPLC or ESI-IMS alone, and thirteen alkaloids were tentatively identified based on m/z and fragment ions using ultra-high-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Hence, our results indicate that this method can be considered to be advantageous over traditional absorbance detection methods for resolving complex mixtures because of complementary separation steps, elevated peak capacity, and higher sensitivity.

Prediction and application of energy absorption characteristics of thin-walled circular tubes based on dimensional analysis

In this paper, the energy absorption characteristics of a circular tube are studied using the dimensional analysis method. First, circular tubes composed of different materials, namely, mild steel and aluminium alloy, are used in this study, and the material parameters are obtained from tensile tests. A finite element simulation model of an energy-absorbing circular tube is established and validated through experiments. Second, the Hammersley sampling method was used to design an experiment for the energy-absorbing circular tube under three deformation modes (i.e., concertina mode, mixed mode and diamond mode). Dimensional analysis of the deformation displacement, energy absorption and mean crushing force of the energy-absorbing circular tube under the three deformation modes was carried out. Relationships between the deformation displacement, energy absorption and mean crushing force of the energy-absorbing circular tube and the parameters of the impact mass, impact velocity, etc. are obtained by fitting the results of the dimensional analysis. The fitting accuracy is greater than 0.95. Next, the energy-absorbing circular tube impact experiments were performed, and the experimental results were compared with the fitting results. The error between the predictions and the experimental results is within 10%, so the prediction results are accurate. Finally, the equivalent substitution method between the aluminium alloy and mild steel energy-absorbing circular tube is discussed. The results show that the equivalence of energy absorption is the best equivalent substitution method for the lightweight design of an energy-absorbing circular tube and the length and diameter of the energy-absorbing circular tube should be held constant to obtain the equivalent thickness.

Experimental Verification of Dimensional Analysis Results on Flow Distribution and Pressure Drop for Disc-Type Windings in OD Cooling Modes

Oil-flow distribution in the winding has a direct impact on cooling performance. In addition, static pressure drop over the winding determines oil split among windings connected hydraulically in parallel. In this paper, experimental verifications are provided to support computational fluid dynamics (CFD) simulations for disc-type windings in oil-forced and directed (OD) cooling modes. Oil-flow distribution in and pressure drop over disc-type winding models are measured using a particle image velocimetry system and a differential pressure instrument, respectively. Dimensional analysis is adopted to analyze the relationship between flow distribution, or pressure drop, and the controlling parameters. CFD parametric sweeps of the dimensionless parameters obtained from the dimensional analysis are conducted and the CFD results are then correlated with the dimensionless parameters. The comparisons between measured results and corresponding results obtained from the correlations demonstrate constant consistency, proving the validity of both the method of dimensional analysis and the correlations. Finally, comparisons of experimental results from isothermal and nonisothermal conditions in OD cooling modes are executed, which show that the isothermal conclusions can be extended to nonisothermal cases because the effects of buoyancy force and hot-streak dynamics prove to be negligible.

A New Robust Carbuncle-Free Roe Scheme for Strong Shock

The paper devises a new robust carbuncle-free Roe Riemann solver for strong shock, different from hybrid method, entropy fix, Liou’s conjecture (J Comput Phys 160:623–648, 2000) and artificial viscosity (Rodionov in J Comput Phys 345:308–329, 2017). Roe scheme encounters carbuncle phenomenon, violates entropy condition and lacks positivity property. The remedy integrates shear viscosity into momentum flux to damp undesirable perturbation and prevents unstable vorticity mode from triggering shock instability. Compared to HLL scheme, shear viscosity is properly established through dimensional analysis and analogy method. The non-linear wave speeds are slightly modified by incorporating the neighboring cell information for positive conservation. The pressure-based sensing function is applied to preserve shear layer while keeping shock robustness. The resulting scheme is very easily implemented by converting the existing Roe code. The matrix stability analysis confirms that this approach is shock-stable and more robust than entropy fix. A series of numerical results demonstrate its potential features: positivity-preserving property, entropy-satisfying property, accurate boundary-layer resolution and high robustness against shock instability. In addition, it signifies that the reason to cause shock instability for Roe scheme may be not the pressure difference term in mass flux, but the inadequate shear viscosity.

Numerical simulation of dynamic characteristics of a water surface vehicle with a blended-wing-body shape

The blended-wing-body shape vehicle is a new type of water surface vehicle with a large square coefficient. The interference of the wave systems under a high speed condition is more significant for the blended-wing-body shape vehicle and the dynamic characteristics of the new type vehicle are very different from that of a traditional vehicle. In this paper, the implicit volume of fluid (VOF) method is adopted to simulate the wave resistance of the high speed blended wing body vehicle, and a semi-relative reference frame method is proposed to compute the maneuvering coefficients. The effects of the navigation speed, the drift angle and the rotating radius are studied. The dimensional analysis method is used to assess the influence of Fr and L/R on the results. The wave making resistance coefficient against the speed sees a large fluctuation because of the serious wave interference. The lateral rotation maneuvering characteristics under the surface navigation condition is nonlinear and more complex than under the under water condition, which is quite different to control.

Study on model design and dynamic similitude relations of vibro-acoustic experiment for elastic cavity

Coupling between aero-acoustic noise and structural vibration under high-speed open cavity flow-induced oscillation may bring about severe random vibration of the structure, and even cause structure to fatigue destruction, which threatens the flight safety. Carrying out the research on vibro-acoustic experiments of scaled down model is an effective means to clarify the effects of high-intensity noise of cavity on structural vibration. Therefore, in allusion to the vibro-acoustic experiments of cavity in wind tunnel, taking typical elastic cavity as the research object, dimensional analysis and finite element method were adopted to establish the similitude relations of structural inherent characteristics and dynamics for distorted model, and verifying the proposed similitude relations by means of experiments and numerical simulation. Research shows that, according to the analysis of scale-down model, the established similitude relations can accurately simulate the structural dynamic characteristics of actual model, which provides theoretic guidance for structural design and vibro-acoustic experiments of scaled down elastic cavity model.

Measuring Elastic Properties of the Constituent Multilayer Coatings for Different Modulation Periods

This paper is developed to characterize mechanical properties of multilayer coatings for different modulation periods. To that end, Dimensional Analysis Method (DAM) and Finite Element Method (FEM) are applied. Based on these methodologies, two dimensionless forms for the new model are expressed. Numerical nanoindentation tests are carried out for different set properties of multilayer coatings in order to validate the proposed model. Therefore, the mechanical properties of multilayer thin films are identified according to the reverse analysis algorithm. Hence, the input and the identified properties are consistent which ensure the effectiveness and the reliability of the proposed model. Moreover, a case study of Ti-TiN multilayer coating deposited on Zr-based metallic glasses was considered. As a result, the new model is useful for multilayer coatings for different modulation periods and can be used for technological applications.

Mass flow rate of fine and cohesive powders under differential air pressure

Air-powder interactions are of practical importance in the production of pharmaceuticals, food and high value added chemicals manufactured using powders. For examples, air-powder effects enable consistent and effective dosing of fine cohesive powders into dies on high productivity rotary presses due to the suction fill effect.A purpose built experimental testing rig was developed and calibrated in order to develop a basic understanding of effect of air pressure on the mass flow rate of fine and cohesive powders. The powder materials were selected to enable the study of the effect of particle properties, such as size and density, and processing conditions such as differential air pressure, on the mass flow rate of powders.The models available in the literature developed for coarse free flowing sands under differential pressure were found inadequate to describe the experimental observations and to predict the flow behaviour of fine and cohesive powders. A new powder flow model was developed using established dimensional analysis methods based on the experimental data. The proposed model includes terms that account for the effect of differential pressure and reduces to the classic Beverloo model in absence of differential pressure. The model was validated and can be used for formulation and process design for flow regimes where air-powder interactions are important.

Numerical studies on the acoustic characteristics of the U-shaped corrugated pipes and application investigations

This paper presents a numerical study on the effect of structural parameters on acoustical transmission loss of U-shaped corrugated pipe using the control variable method. Then, the interactions between the cutoff frequencies and structural parameters are modeled based on the dimension analysis method using the numerical results. An investigation into the application of the U-shaped corrugated pipe into a simple expansion chamber muffler is carried out using both numerical and experimental methods. The results show that the U-shaped corrugated pipes have unique acoustic characteristics in noise attenuation, which resembles a resonant muffler. Furthermore, the numerical results of the transmission loss of U-shaped corrugated pipes are in good agreement with experimental results, which indicates that the transmission loss results obtained by acoustic finite element method is accurate. In addition, the corrugation height, corrugation length, and corrugation internal diameter are the factors that affect the acoustical behavior of the corrugated pipe most significantly. Moreover, the proposed empirical formulas for predicting the cutoff frequencies of U-shaped corrugated pipes are verified with high accuracy and with a prediction error within ±3.0%. What is more, the application of U-shaped corrugated pipes in expansion chamber muffler can effectively reduce the noise in the mid- to high-frequency band, which is useful to reduce the muffler volume and the amount of sound-absorbing material. Hence, automobile mufflers can be designed in a much more environmentally friendly way. In conclusion, this work could provide a theoretical basis for the acoustical design of U-shaped corrugated pipes, and it initiates a new research and application field for corrugated pipes as well.

Determination of Shear Wave Velocity in Offshore Terengganu for Ground Response Analysis

Amount of vibration received in any location can be analysed by conducting ground response analysis. Even though there are three different methods available in this analysis, One Dimensional ground response analysis method has been widely used. Shear wave velocity is one of the key parameters in this analysis. A lot of correlations have been formulated to determine shear wave velocity with cone penetration test. In this study, correlations developed for Quaternary geological age have been selected. Six equations have been adopted comprise of all soil and soil type dependent correlations. Two platforms sites consist of clay and combination of clay and sand have been analysed. Shear velocity to be used in ground response analysis has been obtained. Results have been illustrated in graphs where shear velocity for each case has been plotted. In avoiding under or over predicting of shear wave velocity, the average of all soil and soil type dependent results will be used as final Vs value.

Research on Influence Factors of Tug Cable’s Breaking Force in Narrow Channel

Tug cable directly bears ship’s towage force. It is necessary to study influence factors of tug cable’s breaking force in narrow channel for towage safety. In the present paper, influence factors of tug cable’s breaking force are analyzed by using dimension analysis method. The research results show that tug cable’s breaking force is closely related with dynamic coefficient, Newton number, and Mach number. Half experience and half theory formula of tug cable’s breaking force can be obtained by regression analysis experiment data.

Research on Influence Factors of Tug Cable’s Breaking Force in Narrow Channel

Tug cable directly bears ship’s towage force. It is necessary to study influence factors of tug cable’s breaking force in narrow channel for towage safety. In the present paper, influence factors of tug cable’s breaking force are analyzed by using dimension analysis method. The research results show that tug cable’s breaking force is closely related with dynamic coefficient, Newton number, and Mach number. Half experience and half theory formula of tug cable’s breaking force can be obtained by regression analysis experiment data.

Modeling and prediction of metallic powder behavior in explosive compaction process by using genetic programming method based on dimensionless numbers

Explosive compaction process of metallic powders has been studied using a semi-empirical method. This method utilizes dimensional analysis along with genetic programming approach to obtain an expression relating the final density of compacts to the effective parameters during compaction process such as shock compaction energy, properties of metallic powder, and geometry of the problem and explosive charge. Dimensionless numbers have been constructed based on the effective parameters using a complete set of input–output experimental data. The obtained dimensionless numbers then have been applied as input–output data pairs for genetic programming optimization process considering modeling error as the objective. The obtained results show that the proposed model using dimensional analysis method along with genetic programming can predict the final density of compacts with 99.8% accuracy. Also, the outputs of the proposed model have been compared with those obtained by group method of data handling type neural network in the literature. Consequently, genetic programming method has much less root mean square error than group method of data handling model and can be successfully used for modeling and prediction of the complex process behavior.

3-D Numerical Investigation on Oxygen Transfer in a Horizontal Venturi Flow with Two Holes

In order to investigate the dissolved oxygen increase caused by air suction in a horizontal Venturi flow with two holes, a 3-D computational fluid dynamics model was used to explore the water and bubble mixture flow, coupled with a dissolved oxygen transfer model. A series of experiments were conducted to validate the mathematical model. A relative saturation coefficient correlation was examined factoring in dissolved oxygen concentration at the inlet, water velocity at the inlet, the hole’s diameter, contraction ratio at throat section, and the downstream length of Venturi pipe. It was found that the relative saturation coefficient increases with increasing dissolved oxygen concentration at the inlet and downstream length of Venturi pipe respectively. However, it increases with decreasing water velocity at the inlet and contraction ratio at the throat section to some extent. The hole’s diameter plays a complex role in the relative saturation coefficient. The dimensional analysis method and the least square method were used to deduce a simple formula for the relative saturation coefficient, and this was consistent with related data.