Pivoting based manipulation by a humanoid robot

In this paper we address whole-body manipulation of bulky objects by a humanoid robot. We adopt a “pivoting” manipulation method that allows the humanoid to displace an object without lifting, but by the support of the ground contact. First, the small-time controllability of pivoting is demonstrated. On its basis, an algorithm for collision-free pivoting motion planning is established taking into account the naturalness of motion as nonholonomic constraints. Finally, we present a whole-body motion generation method by a humanoid robot, which is verified by experiments.     

Energy cost of irrigation policy in Morocco: a social accounting matrix assessment

The objective of this study was to assess the consumption and the multiplier effect of the use of energy and irrigation water for rainfed and irrigated agriculture at the national level in Morocco. Using a social accounting matrix, the direct and indirect economic effects of subsidizing energy used by agriculture were identified. The results show that irrigation water policy in Morocco, which targets ‘water-saving’ techniques, has increased the use of subsidized energy and that indirect effects, through energy subsidies, exceed the direct effects of agricultural subsidies. A social accounting matrix can help decision makers make the necessary trade-offs between irrigated and rainfed agriculture.     

Improvement in DTC-SVM of AC drives using a new robust adaptive control algorithm

In this paper a new robust adaptive speed controller algorithm for AC motor drives is presented. The main feature of this algorithm is that minimum synthesis is required to implement the strategy. MCS algorithm is a significant development of MRAC. The stability of the proposed system is achieved through Popov’s Hyperstability criteria. The new algorithm appeared to be robust in the face of totally unknown plant dynamics, external disturbances and parameter variations with the plant. Finally, a new approach has been successfully implemented on DTC-SVM. Extensive simulation results are presented to validate the proposed technique. The system is tested at different speeds and a very satisfactory performance has been achieved.     

Super twisting sliding mode approach applied to voltage orientated control of a stand-alone induction generator

To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.     

Surface integrity analysis of machined Inconel 718 over multiple length scales

Surface integrity characteristics of machined Inconel 718 have been measured using experimental techniques, such as FEG-SEM, EBSD, XRD, TEM, nano-indentation and 3D optical microscopy. Nanosized grains typical of severe plastic deformation are characteristic of the machined surface while deformation in the form of plastic slip bands is typical of subsurface layers. Correlations are presented between deformation features on the machined surface, and cutting parameters and tool wear.     

Electrochemical and photoelectrochemical study of gallium arsenide–polybithiophene composite

Bithiophene (BiTh) was galvanostatically polymerized in the presence of gallium arsenide (GaAs) particles at different concentration. The properties of the composite layers were studied by electrochemical method (cyclic voltammetry), UV–vis spectroscopy and photocurrent measurements. From UV–vis spectroscopy studies, the absorbance of the composites is larger than the polybithiophene absorbance in the UV region. The p-type semiconducting behaviour of the reduced polybithiophene was studied by photocurrent measurements. It was observed that the photocurrents of the composites was higher than that of the PBiTh without GaAs, and increased with GaAs concentration.     

Efficient deterministic method for detecting new U2R attacks

The purpose of this study is to describe an efficient deterministic intrusion detection approach that detects both old and new attacks. We especially focused on detecting the user to root (U2R) attacks of the 1999 DARPA evaluation dataset. The main idea of our approach is to test if an unknown behavior is close enough to a known behavior (attack or normal) such as we can conclude that it belongs to its class. To achieve that, we formulate the problem of intrusion detection as a linear programming system (LPS). The objective function of this LPS leads to minimize the distance between an unknown behavior and one of the known behaviors, by respect of some constraints. The solution of such a problem is a set of bivalent variables x_ij. If (x_ij = 1) then we can conclude that the unknown behavior i belong to the class of behaviors j. Our experiments demonstrated the efficiency of our approach.     

Characterization of the Tunisian phosphogypsum and its valorization in clay bricks

This study concerns the analysis of the incorporation of phosphogypsum (PG) into the fired clay bricks. In Tunisia, for several years, a set of phosphoric acid production factories have produced PG in large quantities (approximately 10 million tons per year). Currently, in Sfax (Center-East of Tunisia), the PG is stored into piles in the vicinity of the factory, by dry or wet process. The storage of PG, even though presenting a low radioactivity, causes pollution to the watertable and to the soil (due to the infiltration of acid and heavy metals). After characterization, the Tunisian PG, which plays the part of a grease-remover, was introduced into the clay bricks with different mass percentages of 0%, 5%, 15%, 25%, 30% and 40%. The study involved physical, chemical, mechanical and environmental tests on the obtained bricks.The obtained results showed that with 30% of PG incorporation, the bricks successfully satisfied the standard requirements. The increase of the percentage of PG resulted in a decrease in the mechanical strengths of these mini-bricks, but it is still higher than the standards limits. The 25% ratio of substitution appeared to be the most effective considering the performed tests.     

Validation of finite element models of liver tissue using micro-CT

In this work, we aim at validating some soft tissue deformation models using high-resolution micro-computed tomography (Micro-CT) images. The imaging technique plays a key role in detecting the tissue deformation details in the contact region between the tissue and the surgical tool (probe) for small force loads and provides good capabilities of creating accurate 3-D models of soft tissues. Surgical simulations rely on accurate representation of the mechanical response of soft tissues subjected to surgical manipulations. Several finite-element models have been suggested to characterize soft tissues. However, validating these models for specific tissues still remain a challenge. In this study, ex vivo lamb liver tissue is chosen to validate the linear elastic model (LEM), the linear viscoelastic model (LVEM), and the neo-Hooke hyperelastic model (NHM). We find that the LEM is more applicable to lamb liver than the LVEM for smaller force loads (< 20 g) and that the NHM is closer to reality than the LVEM for the range of force loads from 5 to 40 g.