Distance-based clustering methods categorize samples by optimizing a global criterion, finding ellipsoid clusters with roughly equal sizes. In contrast, density-based clustering techniques form clusters with arbitrary shapes and sizes by optimizing a local criterion. Most of these methods have several hyper-parameters, and their performance is highly dependent on the hyper-parameter setup. Recently, a Gaussian Density Distance (GDD) approach was proposed to optimize local criteria in terms of distance and density properties of samples. GDD can find clusters with different shapes and sizes without any free parameters. However, it may fail to discover the appropriate clusters due to the interfering of clustered samples in estimating the density and distance properties of remaining unclustered samples. Here, we introduce Adaptive GDD (AGDD), which eliminates the inappropriate effect of clustered samples by adaptively updating the parameters during clustering. It is stable and can identify clusters with various shapes, sizes, and densities without adding extra parameters. The distance metrics calculating the dissimilarity between samples can affect the clustering performance. The effect of different distance measurements is also analyzed on the method. The experimental results conducted on several well-known datasets show the effectiveness of the proposed AGDD method compared to the other well-known clustering methods.

This paper presents behaviour of normal concrete, ultrahigh-strength concrete, engineered cementitious composite, lightweight concrete, self-consolidating concrete and crumb rubber concrete under confinement. Forty-six circular, square and rectangular concrete-filled steel tube columns with varying slenderness are tested under axial compression. Failure modes, axial load– displacement responses and stress– strain characteristics are analysed as well as concrete confined strengths are determined based on experimental results and existing models. The performance of existing confined strength models is evaluated and modified to accommodate different types of high-performance concretes and column shapes. The modified model improves the prediction of confined concrete strength with a mean predicted-to-experimental ratio of 1. 05 as shape and concrete type factors are introduced.

The plasma electrolyte cleaning is an electro-physical process in which a conductive workpiece immerges in an electrolyte and plasma generates on its surface due to passing large currents. Melting the surface locally causes the cleaning of the workpiece’s surface. In this article, the parameters affecting the plasma cleaning process, including current, voltage, duty cycle, frequency, electrolyte temperature, and signal shape are studied. The effects of the parameters on the material removal and the workpiece surface roughness have been studied experimentally. The signals used in this study are DC, pulse DC and AC with asymmetric polarity. In this research, the design of the experiments is performed using the Taguchi method. After the experiments, the results were analyzed by statistical analysis software. Experimental relationships between parameters are also extracted. The experiment results show that in the process of cleaning with direct current, plasma is only formed in a small current range. Using pulse current, the controlability of the process has increased. The effect of current and time of cleaning in the process of plasma cleaning has a great and direct effect on the material removal rate. Alternating current with asymmetric polarity reduces the material removal rate in the electrolytic plasma cleaning process. The surface roughness can be reduced by reducing the percentage of duty cycle, and this process can be used for fine polishing of workpiece surfaces. Maximum removal of materials, and minimum roughness are 30 mg and 0. 5 micrometer respectively.

An extensive experimental study is conducted to examine the effects of different winglet-shapes and orientations on the vortex behind a wing, static surface pressure over the wing, and wake of a swept wing at various angles of attack. Four types of winglets, spiroid (forward and aft), blended, and winggrid are used in this investigation. Wing static surface pressure measurements are obtained for both chordwise and spanwise as well as the wake profiles at various angles of attack using the aforementioned winglets. The data are compared with those without winglet - that is, bare wing. The results show that integration of winglets change the fiowfield over and around the wing significantly. Further, it is found that certain winglet configurations improve both the wake and the wing pressure distribution. The total pressure in the wake of the model varies drastically when the wing is equipped with winglets.

High strength concrete (HSC) provides high strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. This means that a designer should be aware of limiting the amount of tensile reinforcement to prevent the brittle failure of concrete. Therefore the full potential of the use of steel reinforcement cannot be achieved. This paper presents a method to prevent the brittle failure of concrete beams. Five beams made of HSC were cast and tested. The cross section of the beams was 200x300 mm, with a length of 4 m and a clear span of 3.6 m subjected to four-point loading, with emphasis placed on the midspan deflection. The first beam served as a reference beam. The remaining beams had different tensile reinforcement and the confinement shapes were changed to gauge their effectiveness in improving the strength and ductility of the beams. The compressive strength of the concrete was 85 MPa and the tensile strength of the steel was 500 MPa and for the stirrups was 250 MPa. Results of testing the five beams proved that placing helixes with the right diameter and pitch in the compression zone of reinforced concrete beams improve their strength and ductility.

Background an objectivesIn the past, many studies have been carried out on the hydraulics of sliding valves. In addition to flow control and measurement, this structure is used for energy consumption downstream. This structure plays an important role in controlling and regulating the speed downstream of the structure. The supercritical flow passing through sliding valves has attracted the attention of researchers due to its high energy dissipation. The high velocity of the flow in the downstream of the hydraulic structures is one of the important issues of water engineering and usually causes damages if there is no control in the downstream. The creation of hydraulic jump is associated with the transformation of supercritical to subcritical flow, and as a result, energy consumption occurs. This phenomenon can be seen downstream of structures such as dams, rapids and valves. So far, successive methods have been used to reduce the kinetic energy of the flow passing through the sliding valves, which are discussed below. Among the first researches in this field, the studies of Rajaratnam (1967), Rajaratnam (1968) and Alhamid, (1994) can be mentioned. Daneshfaraz et al. (2022a) investigated the hysteretic behavior of the supercritical flow which occurs with two different flow behaviors under the same hydraulic conditions. The results showed in the primary flow, the amount of these depths indicates the subcritical regime, and in the secondary flow, with the formation of the hysteresis phenomenon in some flow rates, it indicates the supercritical regime. The hysteretic phenomenon has a different effect on the amount of energy consumption depending on the type of flow.MethodologyThe experiments were performed in a laboratory flume 5 m long, 0.30 m wide, and 0.45 m deep. The laboratory channel has a floor and walls made of Plexiglass and is equipped with a point depth gauge with an accuracy of ±1 mm. A 1 cm thick sluice gate is installed one meter away from the beginning of the flume. In all experiments, the gate opening was considered constant and equal to 5 cm. The discharge applied in the present study ranged from 700 to 900 l/min. The effect of the threshold with semi-cylindrical, cylindrical, pyramidal, and rectangular cube geometric shapes and with different widths of 5, 7, 10, 15, and 20 cm was investigated experimentally. In the present paper, the sill was installed in the different position, including under, the tangential state downstream and upstream of sliding valve.FindingsThe energy dissipation of the sluice gate was investigated in the non-sill mode and with increasing discharge. Laboratory studies showed that the increase in flow rate caused an increase in the flow speed and consequently the descent number of the supercritical region. As a result, the depth of flow in section A has decreased and it has caused energy consumption downstream of the sliding valve. Energy consumption by installing sill in different positions showed that all four geometries, including semi-cylindrical, cylindrical, pyramidal and rectangular cubic sill, had the maximum energy loss in the position under the valve. Results showed that for undergate sill, the maximum of energy dissipation is related to pyramidal, semi- cylindrical, cylindrical and rectangular cubic sills, respectively. The increase in the jetting streamlines due to the application of the pyramid sill is evident in the tangential position downstream of the valve. The results showed that placing circular sills, including semi-cylindrical and cylindrical, in the downstream of the sliding valve, cause the uniformity of the flow lines. Therefore, the depth of the flow in the initial section of the hydraulic jump is reduced compared to the polygon sills.Conclusion The results showed that:1. The amount of energy loss increases with the increase in sill width.2. Due to having the slope of the downstream side in the same direction as the flow, the pyramid threshold increases the speed of the flow and therefore causes a decrease in the initial depth of the flow.3. Circular sills including semi-cylindrical, cylindrical and rectangular cube were included, respectively, with the greatest initial depth4. By changing the position of the threshold to the tangent position downstream of the sliding valve, the highest amount of energy loss was assigned to semi-cylindrical, cylindrical, rectangular cube and pyramidal thresholds, respectively.

The nonlinear pull-in behavior for different electrostatic micro-actuators is simulated in this work. The difficulty of nonlinear equation is overcome using the differential quadrature method and Wilson−q method. Several characteristics of different combination of shaped fixed-fixed beam and curved electrode are also observed to optimize the design in this paper. The nonlinear deflection of uniform actuator and non-uniform actuator solved using the differential quadrature methods are efficient. The stresses are determined for this par electrostatic micro-actuator design. The effects of applied voltage, squeeze film force, external loading and residual axial loading on the behavior of the electrostatic actuator are investigated. It is needed to consider the squeeze film force and residual axial loading in the fixedfixed micro-actuator design.