Experimental investigation of feedforward control schemes of a flexible robot manipulator system

This paper presents experimental investigations into the applications of feedforward control schemes for vibration control of a flexible manipulator system. Feedforward control schemes based on input shaping and filtering techniques are to be examined. A constrained planar single-link flexible manipulator is considered in this experimental work. An unshaped bang-bang torque input is used to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. The input shapers and filtering techniques are designed based on the properties of the system. Simulation results of the response of the manipulator to the shaped and filtered inputs are presented in time and frequency domains. Performances of the shapers are examined in terms of level of vibration reduction and time response specifications. The effects of derivative order of the input shaper on the performance of the system are investigated. Finally, a comparative assessment of the control strategies is presented and discusse

Finite Element Analyses of Granular Pile Anchors as a Foundation Option for Reactive Soils

Laboratory and field studies have shown that granular pile-anchor foundations (GPAF) are a promising foundation system that can be used to reduce the detrimental effects of reactive soils. This paper presents results from finite element analyses undertaken on granular pile-anchor foundations in a reactive soil using PLAXIS software. The study investigated the ability of a single pile to resist forces induced by both heave and shrinkage. The results confirmed the efficiency of the granular pile-anchor foundations in resisting heave induced by moisture gain. However, in order to resist shrinkage, the GPAF system has to be reinforced with geofabric to assist resisting bulging of the granular pile into the surrounding soil. The analyses showed that success of the GPAF in heave resistance may be adversely influenced by the high stiffness of the interface, which requires only small relative movement to mobilize full resistance. Using a group of piles instead of a single pile under a footing can reduce the efficiency of the GPAF system

Finite Element Modeling of Innovative Shallow Foundation System for Reactive Soils

Granular pile anchor foundations (GPAF) are a promising foundation system that can be used to mitigate the serious consequences of volumetric changes of reactive soils, both during expansion and shrinkage. This paper presents results from 3D finite element analyses, using PLAXIS software, undertaken on a typical double-story building constructed over a system of GPAF in a reactive soil. The study investigates the ability of the GPAF system to resist the forces induced by soil movement due to moisture variation, and the impact of this resistance on the straining actions affecting the superstructure. The results confirm the efficiency of the GPAF system in arresting the movement of the reactive soil, which in turn improves the structural responses of the building in terms of induced deformations, angular distortions and internal forces

GENERALIZED THERMOELASTIC FUNCTIONALLY GRADED HALF SPACE UNDER SURFACE ABSORPTION OF LASER RADIATION

The subject of this paper is to study the thermoelastic behavior of a functionally graded semi-infinite medium heated uniformly by a laser beam having temporally Gaussian distribution. The surface of the medium is taken as traction free. The general solution is obtained in the Laplace transform domain. The inverse of the Laplace transform is computed numerically using the Riemann-sum approximation method. The numerical results for temperature, displacement and stress are obtained and presented graphically for the generalized theory of thermo-elasticity with one relaxation time

Morphological Characteristics of Hardened Cement Pastes Incorporating Nano-palm Oil Fuel Ash

Recently, nano-sized additives and supplementary cementing materials (SCM) have shown to improve the mechanical and durability of mortars and concretes. This study investigates the incorporation of nano-POFA (nPOFA) into cement paste so as to observe its effect towards the microstructure development of cement. Additionally, the effect of micro-sized POFA (mPOFA) was also carried out for comparison. The mPOFA were subjected to milling for the generation of nPOFA. The prepared nPOFA exhibited a BET specific surface area of 145.35 m2/g with an average particle size ranging between 20 nm to 90 nm. Cement pastes were prepared with 10% - 50% replacement of nPOFA and 10% - 30% replacement of mPOFA. The morphological analysis of hardened cement paste (hcp) containing nPOFA (nPOFA-hcp), mPOFA (mPOFA-hcp) at the curing ages of 7, 28 and 90 days were conducted and compared with Ordinary Portland cement paste. At 7 days curing, the nPOFA particles acted as fillers and nucleation sites to accelerate cement hydration. The nPOFA particles reduced the appearance of lime crystals in the nPOFA-hcp at later curing ages due to the occurrence of pozzolanic reactions which formed secondary calcium-silicate-hydrates gel, resulting in a compact microstructure. The study concluded that the nPOFA particles created a dense and closely-packed microstructure of the hardened cement pastes due to the filling effect and pozzolanic reactions in the pastes

Response of Azadirachta Indica and Eucalyptus tereticornis to Bioinoculants (VAM, Phosphobacterium and Azospirillum) in sewage sludge amended soil

Pot culture experiment was conducted in red loamy soil to evaluate the growth response and nutrient uptake of Azadirachta indica and Eucalyptus tereticornis grown in non-amended and sludge amended soil. Sludge application enhanced growth and biomass production of A. indica compared to E. tereticornis. Combined inoculants resulted in a significant increase in plant growth and nutrient uptake. Inoculant effectiveness was higher in tree species grown in sludge-amended soil. The present experiment clearly indicates the feasibility of using inoculation as suitable for conventional fertilizers in the establishment of forest trees

Microphone Array Speech Enhancement Via Beamforming Based Deep Learning Network

In general, in-car speech enhancement is an application of the microphone array speech enhancement in particular acoustic environments. Speech enhancement inside the moving cars is always an interesting topic and the researchers work to create some modules to increase the quality of speech and intelligibility of speech in cars. The passenger dialogue inside the car, the sound of other equipment, and a wide range of interference effects are major challenges in the task of speech separation in-car environment. To overcome this issue, a novel Beamforming based Deep learning Network (Bf-DLN) has been proposed for speech enhancement. Initially, the captured microphone array signals are pre-processed using an Adaptive beamforming technique named Least Constrained Minimum Variance (LCMV). Consequently, the proposed method uses a time-frequency representation to transform the pre-processed data into an image. The smoothed pseudo-Wigner-Ville distribution (SPWVD) is used for converting time-domain speech inputs into images. Convolutional deep belief network (CDBN) is used to extract the most pertinent features from these transformed images. Enhanced Elephant Heard Algorithm (EEHA) is used for selecting the desired source by eliminating the interference source. The experimental result demonstrates the effectiveness of the proposed strategy in removing background noise from the original speech signal. The proposed strategy outperforms existing methods in terms of PESQ, STOI, SSNRI, and SNR. The PESQ of the proposed Bf-DLN has a maximum PESQ of 1.98, whereas existing models like Two-stage Bi-LSTM has 1.82, DNN-C has 1.75 and GCN has 1.68 respectively. The PESQ of the proposed method is 1.75%, 3.15%, and 4.22% better than the existing GCN, DNN-C, and Bi-LSTM techniques. The efficacy of the proposed method is then validated by experiments

An integral equation method for solving neumann problems on simply and multiply connected regions with smooth boundaries

This research presents several new boundary integral equations for the solution of Laplace’s equation with the Neumann boundary condition on both bounded and unbounded multiply connected regions. The integral equations are uniquely solvable Fredholm integral equations of the second kind with the generalized Neumann kernel. The complete discussion of the solvability of the integral equations is also presented. Numerical results obtained show the efficiency of the proposed method when the boundaries of the regions are sufficiently smooth