Robust adaptive cruise control of high speed trains

The cruise control problem of high speed trains in the presence of unknown parameters and external disturbances is considered. In particular a Lyapunov-based robust adaptive controller is presented to achieve asymptotic tracking and disturbance rejection. The system under consideration is nonlinear, MIMO and non-minimum phase. To deal with the limitations arising from the unstable zero-dynamics we do an output redefinition such that the zero-dynamics with respect to new outputs becomes stable. Rigorous stability analyses are presented which establish the boundedness of all the internal states and simultaneously asymptotic stability of the tracking error dynamics. The results are presented for two common configurations of high speed trains, i.e. the DD and PPD designs, based on the multi-body model and are verified by several numerical simulations.     

A novel method to musicalize shape and visualize music and a novel technique in music cryptography

Since many years ago, musicians have composed music based on the images that they have had in their minds. On the other hand, music affects people’s imagination while hearing it. This research provides a method that can transform shape to music and music to shape. This method defines musical notations for horizontal, diagonal and vertical line segments, filled circle and curve with different colors, which are the basis of many shapes in transforming shapes into music. Then these primary mappings are generalized to more complex forms to transform any shape. Moreover, music can be transformed into shape by this method. For this transformation, primary musical notations such as simple notes, notes joined by a legato, notes with a staccato, notes joined by a legato and have crescendo or decrescendo and notes with an accent or a trill are defined. These primary musical notations are generalized to more complex forms to transform any music into shape. Also, the method of this research can be used in music cryptography. It employs mapping of notes in a twelve-tone equal musical system into shapes and mappings of shapes with an equal line width and different colors into music.

     

Evaluation of Water Balance in a Mountainous Upland Catchment Using SEBAL Approach

Scarcity of water is now the biggest threat in many parts of the world, specially in arid and semi arid regions. Establishing balance between water resources and the demands in a catchment scale basis could be one of the most important strategies to overcome this problem. In this regard, determination and analysis of water balance components (inputs and outputs) would be necessary. This study has focused on estimation of water balance components in arid-mountainous catchment of Manshad in Yazd province of Iran, during the year 2006–2007 using remote sensing and GIS techniques. To estimate actual evapotranspiration (ET_a) of the catchment, time series of MODIS images were obtained and used via Surface Energy Balance Algorithm for Land (SEBAL) approach. Measured precipitation (P) and runoff (R) data of the catchment were also used to calculate water balance equation components. Results indicated that a large volume of catchment water (about 70%) is wasted through evapotranspiration, while the rainfall is not enough to compensate this volume of water during the year. It seems that the negative (descending) trend has become dominant to the water budget of the area and gradually moves to harsh conditions of water shortage in future decades. Therefore, some actions would be necessary to overcome the problem. Water conservation strategies‚ improvement of water use efficiency, and control on agricultural field expansions are some solutions that could be advised for the studied catchment.     

Novel probabilistic bounds on power level profile of spectrally-encoded spread-time CDMA signals

In this letter we introduce an effective tool to demonstrate signal power behavior of a typical spectrallyencoded spread-time (SE/ST) CDMA system using probabilistic approach. By defining power level profile (PLP), as the probability of stretching instantaneous power from a pre-specified threshold, we can find novel upper bounds on the signal power profile. We discuss various properties owing to PLP and elaborate on the main parameters affecting the PLP value. We present three theorems, propose some simple upper bounds on the PLP, and give an insight on the main contributions of the results. We introduce a fundamental parameter, namely β, as a key design parameter which relates the most important quantities affecting the PLP behavior. Finally, we propose a corollary demonstrating an approach to guarantee that the PLP value is set at zero. It is shown that using suitable distributions, we can also obtain some distribution gain, thereby enhancing the overall system performance.     

Supplier's optimal bidding strategy in electricity pay-as-bid auction: Comparison of the Q-learning and a model-based approach

In this paper, the bidding decision making problem in electricity pay-as-bid auction is studied from a supplier's point of view. The bidding problem is a complicated task, because of suppliers’ uncertain behaviors and demand fluctuation. In a specific case, in which, the market clearing price (MCP) is considered as a continuous random variable with a known probability distribution function (PDF), an analytic solution is proposed. The suggested solution is generalized to consider the effect of supplier market power due to transmission congestion. As a result, an algebraic equation is developed to compute optimal offering price. The basic assumption in this approach is to take the known probabilistic model for the MCP.     

Tightly trapped highly excited Rydberg atom in dipole–quadrupole potential landscape

ABSTRACT

In this paper, coherent Rydberg excitation of a single four-level atom in tightly confining trap so-called ‘far-off-resonance optical dipole-quadrupole trap’ (FORDQT) by considering Laguerre Gaussian (LG) beams spatial features is demonstrated. The self-trapping potential results from the position dependent differential AC Stark shift of the ground state and Rydberg state in the effective quadrupole Rydberg excitation. By introducing the effective stiffness of the FORDQT potential in terms of the key parameters of the first and Rydberg excitation laser beams, a technique to obtain sub-micron localization of Rydberg excitation is explored. The complete matched trapping potential of the ground state and Rydberg state near the center of the trap maintains the coherence of the Rydberg excitation. Transfer of optical orbital angular momentum from the LG-beam to the Rydberg-state via localized effective quadrupole excitation process paves the way for implementation of high fidelity qudit gates in high dimensional quantum information process.     

Tubular channel angular pressing (TCAP) as a novel severe plastic deformation method for cylindrical tubes

A severe plastic deformation (SPD) technique based on tubular channel angular pressing (TCAP) is proposed suitable for deforming cylindrical tubes to extremely large strains without changing their dimensions. The tube constrained by inner and outer dies is pressed by a hollow cylindrical punch into a tubular angular channel with three shear zones. This technique was applied to a commercial AZ91 magnesium alloy and a significant grain refinement was achieved even after single cycle TCAP. Microhardness of the tube increased to 78 Hv from an initial value of 51 Hv. This new SPD process is promising for future industrial applications.     

A numerical and experimental study on tubular channel angular pressing (TCAP) process

Tubular channel angular pressing (TCAP) is a new and novel severe plastic deformation (SPD) technique suitable for fabrication of bulk nanograined tubular materials. There are several parameters in the TCAP process. The present paper investigates the effects of curvature angles, deformation ratio (maximum radius during TCAP/initial radius) and deformation direction on the plastic deformation behavior, strain homogeneity and required loads in TCAP processing. The results showed that higher curvature angles (?? ₁ and ?? ₃) leads to better strain homogeneity while have not having any significant effect on the process loads. Also, at the second curvature angle of 90°, the best condition is achieved with good strain homogeneity and lower load requirements rather than lower angles. Investigation of deformation direction showed that inlet deformation direction causes tube thinning at the end of the process, and thus, using the inlet case is not recommended.     

Influence of polyethyleneimine layer and zinc nitrate on morphology and structure of PES-based membranes with highly selective properties

In this paper, nanofiltration (NF) polymer membranes based on polyestersulphone (PES) were prepared by the phase inversion method. Polyethyleneimine (PEI) and zinc nitrate (Zn(NO₃)₂) as a surface modifier and glutealdehyde (GA) as cross-linker was used. Fourier transform infrared spectroscopy analysis (FTIR) was used to confirm the chemical composition on the membrane surface. Membranes were also characterized using field emission scanning electron microscopy (FESEM) and 3D surface images. Water contact angle, average pore size and porosity measurements, water flux, salt rejection, and membrane anti-fouling ability were discussed. Modified membranes showed a smoother surface than the original membrane. The amount of pure water flux decreased with increasing the concentration of modifiers at the surface, but the yield of Na₂SO₄ salt increased, 53% in virgin membrane and 83% in M3 membrane. Modified membranes had better anti-fouling and hydrophilicity properties than primary membranes. The lowest contact angle value was 26.2° for M4. Also, the best anti-clogging comparable properties were for the M3 membrane with FRR = 63.37%, R_r = 10.69%, R_ir = 36.6%, and R_t = 47.3%. By increasing the concentration of modifiers, the removal of CuNO₃⁻ and CuSO₄ improved that the M1 membrane (97.59%) had the highest Cu(NO₃)₂ separation and the M4 membrane (87.5%) had the most increased CuSO₄ separation.