Assessment of the flexural capacity of RC beam/column elements allowing for 3d effects

The paper describes an experimental investigation of the deformational response and the stress conditions developing in the compressive zone of reinforced concrete beam-like structural elements in bending and bending combined with axial force. The results obtained confirm the findings of earlier work and demonstrate that the compressive zone at its ultimate-limit state is characterised by the development of triaxial rather than uniaxial-as widely considered-stress conditions. These findings form the basis for introducing a simple modification in the method currently used for calculating flexural capacity and it is shown that, by complementing the proposed method with an approach that takes into account the effect of yielding of the compression reinforcement on structural behaviour, it is possible to achieve predictions of flexural capacity which are considerably closer to experimentally established values than the values obtained through the use of currently adopted methods.     

Development and testing of a high precision digital Gaussian generator for Computers

A high precision generator of Gaussian distributed pseudorandom numbers has been developed and tested. The generator is designed so that to be suitable for use with computers in simulation applications. Experimental results are given which verify the theoretically predicted performance. The generator approximates with high accuracy the tails of the Gaussian density and this makes it suitable for simulations of rare events. Depending on the system parameters the originally generated densities can be produced in a form which allows computer scaling without affecting the accuracy over a range of more than $\text{+5}$ standard deviations from the mean.     

Highly Efficient,Bright, and Stable Colloidal Quantum Dot Short‐Wave Infrared Light‐Emitting Diodes

Unbalanced charge injection is deleterious for the performance of colloidal quantum dot (CQD) light‐emitting diodes (LEDs) as it deteriorates the quantum efficiency, brightness, and operational lifetime. CQD LEDs emitting in the infrared have previously achieved high quantum efficiencies but only when driven to emit in the low‐radiance regime. At higher radiance levels, required for practical applications, the efficiency decreased dramatically in view of the notorious efficiency droop. Here, a novel methodology is reported to regulate charge supply in multinary bandgap CQD composites that facilitates improved charge balance. The current approach is based on engineering the energetic potential landscape at the supra‐nanocrystalline level that has allowed to report short‐wave infrared PbS CQD LEDs with record‐high external quantum efficiency in excess of 8%, most importantly, at a radiance level of ≈5 W sr^?1 m², an order of magnitude higher than prior reports. Furthermore, the balanced charge injection and Auger recombination reduction has led to unprecedentedly high operational stability with radiance half‐life of 26 068 h at a radiance of 1 W sr^?1 m^?2.     

MoS2–HgTe Quantum Dot Hybrid Photodetectors beyond 2 µm

Mercury telluride (HgTe) colloidal quantum dots (CQDs) have been developed as promising materials for the short and mid‐wave infrared photodetection applications because of their low cost, solution processing, and size tunable absorption in the short wave and mid‐infrared spectrum. However, the low mobility and poor photogain have limited the responsivity of HgTe CQD‐based photodetectors to only tens of mA W^?1. Here, HgTe CQDs are integrated on a TiO₂ encapsulated MoS₂ transistor channel to form hybrid phototransistors with high responsivity of ≈10⁶ A W^?1, the highest reported to date for HgTe QDs. By operating the phototransistor in the depletion regime enabled by the gate modulated current of MoS₂, the noise current is significantly suppressed, leading to an experimentally measured specific detectivity D* of ≈10¹² Jones at a wavelength of 2 µm. This work demonstrates for the first time the potential of the hybrid 2D/QD detector technology in reaching out to wavelengths beyond 2 µm with compelling sensitivity.     

Effect of substrate concentration on fermentative hydrogen production from sweet sorghum extract

The aim of the present study was to assess the influence of substrate concentration on the fermentative hydrogen production from sweet sorghum extract, in a continuous stirred tank bioreactor. The reactor was operated at a Hydraulic Retention Time (HRT) of 12 h and carbohydrate concentrations ranging from 9.89 to 20.99 g/L, in glucose equivalents. The maximum hydrogen production rate and yield were obtained at the concentration of 17.50 g carbohydrates/L and were 2.93 ± 0.09 L H₂/L reactor/d and 0.74 ± 0.02 mol H₂/mol glucose consumed, corresponding to 8.81 ± 0.02 L H₂/kg sweet sorghum, respectively. The main metabolic product at all steady states was butyric acid, while ethanol production was high at high substrate concentrations. The experiments showed that hydrogen productivity depends significantly on the initial carbohydrate concentration, which also influences the distribution of the metabolic products.     

Classical and alternative fuel mix optimization in cement production using mathematical programming

In this paper a systematic methodology is presented for the simultaneous optimal selection of raw materials, fossil fuels and alternative fuels in cement production. The aim is to offer a generic mathematical formulation that can be used as the basis for developing case specific mathematical formulations that can assist the strategic decision-making process. The mathematical model presented takes into consideration the essential elements of a cement plant operation. The final formulation is a mixed integer linear programming problem that aims at minimizing the overall operating cost. A realistic case study is presented which demonstrates the usefulness of the proposed mathematical programming methodology.