Influence of Particle Size Distribution,Moisture Content,and Particle Shape on the Flow Properties of Bulk Solids

Abstract

There has been a great deal of research on characterising bulk solids. However, some of the characteristics, particularly the time‐dependent and random changes of properties, still remain insufficiently understood. The focus of this article is to study the influence of particle size, size distribution, moisture content, and particle shape on the unconfined yield strength of bulk solids. We present some interesting results about the influence of the particle size distribution on the unconfined yield strength of a bulk solid and a new method for determining the influence of particle shape on the unconfined yield strength of a bulk solid, which was made possible by the design and use of a novel attritor.     

The Role of Vitamin A in Retinal Diseases

Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is essential for several physiological processes. Either hyper- or hypovitaminosis can be harmful. One of the most important vitamin A functions is its involvement in visual phototransduction, where it serves as the crucial part of photopigment, the first molecule in the process of transforming photons of light into electrical signals. In this process, large quantities of vitamin A in the form of 11-cis-retinal are being isomerized to all-trans-retinal and then quickly recycled back to 11-cis-retinal. Complex machinery of transporters and enzymes is involved in this process (i.e., the visual cycle). Any fault in the machinery may not only reduce the efficiency of visual detection but also cause the accumulation of toxic chemicals in the retina. This review provides a comprehensive overview of diseases that are directly or indirectly connected with vitamin A pathways in the retina. It includes the pathophysiological background and clinical presentation of each disease and summarizes the already existing therapeutic and prospective interventions.     

Cleaner bioprocesses for promoting zero-emission biofuels production in Vojvodina

In this study, the policy, market conditions and food security of biomass energy sources are assessed for supplying the future needs of Vojvodina. The Autonomous Province of Vojvodina is an autonomous province in Serbia, containing about 27% of its total population according to the 2002 Census. It is located in the northern part of the country, in the Pannonia plain, in southeastern Europe. Vojvodina is an energy-deficient province. The incentives to invest human and financial resources in the research and development of cleaner bioprocesses are high, considering the benefits which might be achieved in terms of environment protection and manufacturing costs. In the near and medium tenu, the development of bioprocesses for waste recycling and resource recovery might be one of the most viable options, considering much research work has already been done. In Vojvodina, there are technological solutions that biofuels produced in a closed cycle, so that the quantity of waste reduced to a minimum. These solutions include the stillage (remainder after distillation) used for fattening cattle, and cattle excrement to produce biogas and manure as fertilizer. The energy required for the production of bioethanol is obtained combustion lignocelullose residual waste from the production of basic raw materials starch, or biogas. Ash from the burned biomass returned to soil as a source of minerals for plants and replacement of mineral fertilizer. Such a closed cycle is economical for small farms in Vojvodina.     

Predicting Chemical Parameters of River Water Quality from Bioindicator Data

We address the problem of inferring chemical parameters of river water quality from biological ones. This task is important for enabling selective chemical monitoring of river water quality. We apply machine learning, in particular regression tree induction, to biological and chemical data on the water quality of Slovenian rivers. Regression trees are constructed that predict values of chemical parameters from data on the presence of bioindicator taxa at the species and family levels.     

The influence of the coordinate reduction on the identification of the joint dynamic properties

A problem of establishing a theoretical model of a joint from the measured frequency-response function (FRF) data is discussed in this paper. The model of the joint is considered as a coupled dynamic stiffness matrix, which generally includes six degrees of freedom (DoFs). For two types of least-squares solution the terms of use are clarified. The effect of coordinate reduction on the identification results is demonstrated numerically. Also the effect of added noise is studied. Using a substructure synthesis method and the identified joint dynamic properties the assembly response is reconstructed.     

DiPAMP’s Big Brother “i‐Pr‐SMS‐Phos” Exhibits Exceptional Features Enhancing Rhodium(I)‐Catalyzed Hydrogenation of Olefins

Switching Knowles DiPAMP’s {DiPAMP=1,2‐bis[(o‐anisyl)(phenyl)phosphino]‐ ethane} MeO groups with i‐PrO ones led to the i‐Pr‐SMS‐Phos {i‐Pr‐SMS‐Phos=1,2‐bis[(o‐isoprop‐ oxyphenyl)(phenyl)phosphino]ethane} ligand which displayed a boosted catalyst activity coupled with an enhanced enantioselectivity in the rhodium(I)‐catalyzed hydrogenation of a wide‐range of representative olefinic substrates (dehydro‐α‐amido acids, itaconates, acrylates, enamides, enol acetates, α,α‐diarylethylenes, etc). The rhodium(I)‐(i‐Pr‐SMS‐Phos) catalytic profile was investigated revealing its structural attributes and robustness, and in contrast to the usual trend, ³¹P NMR analysis revealed that its methyl (Z)‐α‐acetamidocinnamate (MAC) adduct consisted of a reversed diastereomeric ratio of 1.4:1 in favour of the most reactive diastereomer.     

Flow through packed bed reactors: 2. Two-phase concurrent downflow

A model for the prediction of pressure drop and liquid holdup for trickling flow in packed bed reactors has been developed, based on the relative permeability concept. The relative permeabilities for gas and liquid as functions of corresponding phase saturations have been studied with 1300 newly measured data pairs of pressure drop and liquid holdup obtained for a wide range of commercially relevant operating conditions (including pressures up to 50 bar) as well as types of packing (both in terms of size and shape). The relative permeabilities are found to be solely the functions of corresponding phase saturations and it is shown that the functional form of the correlations developed, which are otherwise purely empirical by nature, has its roots in the physics of flow at the microscale level. The proposed model requires no prior experimental knowledge about the packed bed and is able to predict liquid holdup and pressure drop to within 5% and 20%, respectively, regardless of the type of packing or operating range investigated.     

Plasma‐activated methane partial oxidation reaction to oxygenate platform chemicals over Fe,Mo, Pd and zeolite catalysts

Natural gas from stranded sources is being predominantly flared, and there is a growing demand for new technologies for its utilisation, where electrification, flexibility, and modularity play an important role. Plasma‐activated methane partial oxidation reaction was studied in a designed dielectric barrier discharge ionisation reactor unit, producing value‐added platform chemicals, namely, methanol, formaldehyde, intermediate formic acid, acetic acid, and paraformaldehyde at ambient temperature and atmospheric pressure. The effects of various process parameters, such as voltage, total convertible gas flow rate, and reagent ratio relationship, were considered. In addition, coupling of the following catalytic materials with plasma was examined: alumina (Al₂O₃), chabazite, ferrierite, microporous beta zeolite, silica (SiO₂) glass beads, ZSM‐5 (MFI), Fe on H‐ZSM‐5 and Al₂O₃, Mo on H‐ZSM‐5, TiO₂ and SiO₂, and Pd on Al₂O₃. In the liquid product, 21.5% CH₃OH, 20.4% CH₂O, 0.3% HCOOH, and 2.4% CH₃COOH were measured when using pure plasma, and a maximum aggregate yield of the organic oxygenate compounds of 5.21 mol.% was achieved. The usage of shaped silicate surface increased the selectivity towards synthesised oxygen‐containing structures, while the application of alumino‐silicate mixture constituents reduced it. It was determined that elementary covalently bonded carbon was formed inside pores when pure zeolites were used. Fe‐ and Pd‐based heterogeneous catalysts favoured the complete exothermic combustion of CH₄ feedstock reactant species, and the liquid product consisted only of water in the Pd‐ case. The utilisation of Mo/H‐ZSM‐5 resulted in a 46% increased yield of formalin. A mechanism for the role of Mo was proposed, where Mo oxidises methanol to formaldehyde and the metal is reoxidised in plasma.     

Interactive Large‐Scale Procedural Forest Construction and Visualization Based on Particle Flow Simulation

Interactive visualization of large forest scenes is challenging due to the large amount of geometric detail that needs to be generated and stored, particularly in scenarios with a moving observer such as forest walkthroughs or overflights. Here, we present a new method for large‐scale procedural forest generation and visualization at interactive rates. We propose a hybrid approach by combining geometry‐based and volumetric modelling techniques with gradually transitioning level of detail (LOD). Nearer trees are constructed using an extended particle flow algorithm, in which particle trails outline the tree ramification in an inverse direction, i.e. from the leaves towards the roots. Reduced geometric representation of a tree is obtained by subsampling the trails. For distant trees, a new volumetric rendering technique in pixel‐space is introduced, which avoids geometry formation altogether and enables visualization of vast forest areas with millions of unique trees. We demonstrate that a GPU‐based implementation of the proposed method provides interactive frame rates in forest overflight scenarios, where new trees are constructed and their LOD adjusted on the fly.