A dynamic programming method for analysis of bridges under multiple moving loads

A dynamic programming (DP) method is presented for analysis of statically determinate and indeterminate bridges subjected to moving loads such as those specified by the American Association of State Highway and Transportation Officials (AASHTO) specifications. These loads consist of uniform lane loading, two-axle truck loading and two-axle truck plus one-axle semitrailer loading. The solution of the DP problem is based on the use of influence line diagrams and extremum functions. Recurrence formulae have been developed for various types of AASHTO live loads. The procedure presented in this article is quite general and can be applied to any type of structures with linear behaviour and any type of moving loads. Six examples are presented: a simply-supported beam, a simply-supported Pratt truss, an arch bridge, a continuous Pratt truss, a continuous frame and a cable-stayed bridge.     

Wavelet-Hybrid Feedback Linear Mean Squared Algorithm for Robust Control of Cable-Stayed Bridges

Cable-stayed bridges are flexible structures, and control of their vibrations is an important consideration and a challenging problem. In this paper, the wavelet-hybrid feedback least mean squared algorithm recently developed by the writers is used for vibration control of cable-stayed bridges under various seismic excitations. The effectiveness of the algorithm is investigated through numerical simulation using a benchmark control problem created based on an actual semifan-type cable-stayed bridge design. The performance of the algorithm is compared with that of a sample linear quadratic Gaussian (LQG) controller using three different earthquake records: the El Centro (California, 1940), Mexico City (Mexico, 1985), and Gebze (Turkey, 1999) earthquakes. Simulation results demonstrate that the new algorithm is consistently more effective than the sample LQG controller for all three earthquake records. Additional numerical simulations are performed to evaluate the sensitivity of the new control algorithm. It is concluded that the algorithm is robust against the uncertainties existing in modeling structures.     

Sustainability in highrise building design and construction

This paper presents a review of the recent literature on sustainability in construction and design with a focus on highrise buildings. The paper is divided into the following main sections: energy consumption, environmental effects and green practices for highrise buildings. A number of concepts in sustainable design are reviewed including passive solar design, renewable energy resources, cogeneration and tri‐generations, embodied energy reduction, net zero energy building, carbon emission reduction, envelope environment quality, green materials, efficient mechanical design and innovative structural systems. Their applications in a dozen signature and iconic structures are described. In order to achieve net zero energy in a new highrise building, first, multiple green solutions need to be evaluated using two categorical solutions: passive solar and envelop environment design and renewable energy resources along with efficient energy generators. Next, a robust optimization algorithm should be used to select the optimum set of solutions. This is worth pursuing in future sustainable design of highrise buildings because they are massive and complex structures with many components. Copyright © 2016 John Wiley & Sons, Ltd.     

Combining continuous catalytic regenerative naphtha reformer with thermally coupled concept for improving the process yield

Advancements in the catalytic naphtha reforming process, as one of the main processes in petrochemical industry, contributed to development of continuous catalytic regenerative naphtha reformer units. Increasing the yield of aromatic and hydrogen as well as saving the energy in this process through the application of thermal coupling technique is a potentially interesting idea. This novel idea has been assessed in this paper. In the proposed configuration, continuous catalyst regeneration naphtha reforming process is coupled with hydrogenation of nitrobenzene in a two co-axial reactor separated by a solid wall, where the generated heat in nitrobenzene hydrogenation reaction transfers to naphtha reforming reaction medium through the surface of the tube. A steady-state, homogeneous, two-dimensional model is used to describe the performance of this configuration and a kinetic model including 32 pseudo-components with 84 reactions is considered for naphtha reforming reaction. After validating the model with the commercial data of a domestic plant, the obtained results of coupled reactor are compared by the conventional one. The obtained results show the superiority of CCR coupled reactor against the conventional one.     

The effect of pH,salts and sugars on the rheological properties of cress seed (Lepidium sativum) gum

Effect of shear rate (15–600 s^?1), gum concentration (1–2%), pH (3–9), sucrose (10–40%), lactose (5–15%), NaCl (100–300 mm ) and CaCl₂ (5–50 mm ) was evaluated on apparent viscosity (η_a), flow behaviour index (n), consistency coefficient (K) and yield stress (τ₀) indices of cress seed gum (CSG) solutions. Different rheological models were used to fit the experimental data, although the Herschel–Bulkley model was found the best model. An increase in gum concentration led to an increase in τ₀, η_a, and k and a decrease in n values. The addition of salts lowered the k value; however, the n value showed slight significant change. The presence of sugar resulted in the enhancement of n, k, τ₀ and η_ap values. The existence of yield stress and pseudoplastic behaviour of CSG, its stability against salts, wide range of pH and synergic effect of sugar make it a good thickener and stabiliser in food formulations.     

Ionic liquid catalyzed synthesis of organosoluble wholly aromatic optically active polyamides

A series of optically active wholly aromatic polyamides (PAs) with amino acid moieties in the pendant groups have been synthesized through polycondensation of a chiral diacid and aromatic diamines in an ionic liquid (IL) as a green, safe and eco-friendly medium and also reactions catalysis agent (method I). Furthermore, the polymerization reactions were performed via conventional polycondensation (method II) and obtained results have been compared. Evaluation of data shows that IL is the better polyamidation medium and catalysis stand on the higher inherent viscosities and yields of the obtained PAs and the rate of polymerizations beyond the greener reaction conditions and deletion of some essential reagents in conventional manners. Characterization were performs by means of ¹H-NMR and FT-IR spectroscopy, elemental analysis, thermogravimetric analysis and differential scanning calorimetric techniques.