Experimental tests of a new hysteretic damper made of buckling inhibited shear panels

Metal shear panels represent a highly performing anti seismic system for medium–high rise buildings located in strong earthquake prone zones. A new configuration of dissipative shear panel is presented in the current paper. The base shear plate is made of a low-strength material, namely the heath treated EN-AW-1050A aluminium alloy, which has been already used by the authors for other types of dissipative shear panels. In this proposed new system, the main buckling modes are inhibited by the application of external devices placed in parallel to the base plate and not directly loaded by the external forces. Two shear panel samples are tested as prototypes, which are based on two different plate buckling inhibition strategies. In the former the out-of-plane displacements of only some parts of the base plate are restrained, whereas in the latter the restraining action of the external device is extended to the whole base plate. Experimental tests are presented in order to prove the performance of the proposed devices in terms of dissipative capacity and stiffness. In addition, the obtained results are compared with the ones related to other more conventional shear panel typologies, characterized by the same geometry and material, but in which buckling phenomena were mitigated by means of welded stiffeners, according to a more traditional practice.     

Using hot-vapor bypass for pressure control in distillation columns

Distillation column control is widely explored in literature due to its complexity and importance in chemical and petrochemical industries.In this process,pressure represents one of the most important variables to be controlled.However,there are few studies about how pressure affects the dynamic behavior of distillation columns and most research on distillation column control involve direct manipulation of cooling fluid through the condenser.Nevertheless,such an approach demands constant changes in cooling fluid flowrates that are commonly by the order of tons per hour,which can be difficult to work or even unfeasible in a real plant.Furthermore,this strategy is usually avoided,as it can cause fouling and corrosion acceleration.The hot-vapor bypass strategy fits well as a solution for these issues,eliminating the need to dynamically manipulate cooling fluid flowrates in the condensation unit.This work presents the modeling and simulation of a conventional distillation column for the separation of water and ethanol,in which a comparative study between a conventional pressure control and a control using hot-vapor bypass was performed.The main results were obtained through dynamic simulations which considered various disturbances in the feed stream,and demonstrated superior performance by the hot-vapor bypass system over the usual scheme proposed in literature,while evaluating the Integral Absolute Error (IAE) norm as the control performance index.     

Assessment of Sorghum Malt Sprout Acid Hydrolysates as Organic Nitrogenous Base for the Cultivation of Saccharomyces Cerevisiae

The effects of method of hydrolysis and source of sorghum sprout (sorghum cultivar) on the nitrogen and mineral contents of acid digests from three commercial malting varieties of sorghum were assessed. The mineral and nitrogen contents and constituents of the digests varied significantly (p < 0.05) with respect to the method of digestion, sprout source and the pair-wise interaction of the two factors. Higher digest nitrogen, in both ICSV 400 and SK 5912, was supported by acid digestion in the autoclave while reflux digestion produced higher nitrogen in KSV 8. Of all the digests, those from ICSV 400 (both reflux and autoclave) displayed the best balance of yeast-essential acids as well as superior growth-promoting activity. In their growth-producing activity, the digests also compared very favourably with seven commercial nitrogenous bases used industrially for yeast cultivation. Results suggest that sorghum sprout acid digests are good alternative sources for nitrogen and mineral nutrients in media for microbial cultivation.     

Microcasting of Al bronze: influence of casting parameters on the microstructure and the mechanical properties

In this work the influence of the casting parameters on the microstructure and the mechanical properties of extremely small parts produced by microcasting was investigated. Different specimens were cast using an aluminum bronze with a composition defined by DIN EN 17 665. It was found that the yield stress and the ultimate tensile strength of micro-tensile test specimens increase when decreasing the mold temperature from 1,000 to 700°C. This correlates with the increasing fineness of the microstructure. Additionally, the investigation showed that the mechanical strength of micro-specimens is higher than the one of macro-specimens cast at the same mold temperature due to a finer microstructure which hinders dislocation movement.     

The chemical composition and some physical properties of a water-soluble gum from Prosopis africana seeds

A water‐soluble gum was extracted from the endocarp capsule of the seed coat of Prosopis africana. The gum yield varied substantially with the method of dehulling. Maximum yield was obtained after boiling in 0.1 m Na₂CO₃ for 4 h. The effects of two different gum concentrations on the rheological properties of gum solutions were examined. The gum formed viscous solutions at low concentrations and exhibited stable viscosity in the pH range 6.0–8.0. Chemical analyses showed that the purified gum had a composition of 2.4% fat, 1.04% protein, 21.5% crude fibre and a gelation concentration of at least 10%. Galactose and mannose were the major polysaccharides identified. Large reductions in viscosity were observed with the addition of various concentrations of Na⁺ salts. The activation energies of flow for 2 and 3% gum solutions were in the range of 19.2–22.8 kJ mol^?1 and were characteristic of systems with little intra‐ and intermolecular interactions.     

Seismic performance of MR frames protected by viscous or hysteretic dampers

This study concerns the behaviour of steel frames protected by different anti‐seismic devices (dampers). Typical hysteretic and viscous dampers are arranged in three steel moment‐resisting frames (MRFs) having different dynamical features but are designed to accomplish determined performance objectives. The proposed devices are selected following an iterative procedure based on the use of a suitable damage functional, which has been applied to control the behaviour of the protected structures under a specific seismic record. The outcomes obtained by implementing incremental dynamic analyses, carried out on the basis of seven historical records characterized by different features, allow to analyse the improvement of the structural performance due to the considered dampers and, therefore, to provide design information about their employment. The comparison of results is carried out taking into account the dampers capacity to protect the structures from damage, the inter‐storey drifts, the residual deformations and the possible amplification effects. In conclusion, the equivalent behaviour factors for each damper type are given, with the aim of providing useful design parameters for the implementation of simplified conventional linear analyses. Copyright © 2014 John Wiley & Sons, Ltd.     

DURATION OF FINAL WARM STEEP AS A CRUCIAL FACTOR IN PROTEIN MODIFICATION IN SORGHUM MALTS

Cold water soluble protein (CWS-protein), cold water soluble protein modification index, total non-protein nitrogen (TNPN), small peptide accumulation, free alpha amino nitrogen, carboxy-peptidase and proteinase activities, all protein modification indicators in malts from two improved Nigerian sorghum cultivars were estimated after six days of malting. Grains were steeped in distilled water for a total of 48 h under four different final warm steep (40°C) treatment periods. Cultivar and duration of final warm water steep, plus their pair-wise interactions highly significantly influenced all these protein modification indices. Sorghum ICSV 400 generally exhibited higher FAN, CWS-protein solubilising activity and accumulation, superior amylolytic potential over proteolysis and better protein modification potential over KSV 8. Lower TNPN and TNPN-FAN difference exhibited by ICSV 400 in spite of its higher FAN suggests superior anabolic protein turnover probably due to more efficient peptide translocation process. Proteolytic activities recorded for both cultivars were inconsistent with levels of N-substances obtained suggesting roles for factors other than proteolysis in grain protein modification.     

Purification and Some Properties of a Protease from Sorghum Malt Variety KSV8–11

A protease from sorghum malt variety KSV8–11 was purified by a combination of dialysis against 4 M sucrose, ion‐exchange chromatography on Q‐Sepharose (Fast flow), gel filtration chromatography on Sephadex G‐100 and hydrophobic interaction chromatography on Phenyl Sepharose CL‐4B. The enzyme was purified 5‐fold to give a 14.1% yield relative to the total activity in the crude extract and a final specific activity of 1348.9 U mg^?1 protein. SDS‐PAGE revealed a single migrating protein band corresponding to a relative molecular mass of 16 KDa. Using casein as substrate, the purified protease had optimal activity at 50°C and maximal temperature stability between 30°C and 40°C but retained over 64% of its original activity after incubation at 60°C for 30 min. The pH optimum was 5.0 with maximum stability at pH 6.0 but 60% of the activity remained after 24 h between pH 5.0 and 8.0. The protease was inhibited by Ag⁺, Ca²⁺, Co²⁺, Fe²⁺, Mg²⁺, iodoacetic acid (IAA) and p‐chloromercuribenzoate (p‐CMB), stimulated by Cu²⁺, Sr²⁺, phenylmethylsulfonyl‐fluoride (PMSF) and 2‐mercaptoethanol (2‐ME) while Mn²⁺ and ethylenediaminetetraacetic acid (EDTA) had no effect. The purified enzyme had a K_m of 18 mg·mL^?1 and a V_max of 11.1 μmol · mL^?1 · min^?1 with casein as substrate.     

Perikinetics and sludge study for the decontamination of petroleum produced water (PW) using novel mucuna seed extract

In this study.Mucuna flagellipes seed extract was applied in the coagulation—flocculation of produced water(PW).Process parameters such as pH.dosage,and settling time were investigated.Process kinetics was also studied.Instrumental characterization of mucuna seed(MS),mucuna seed coagulant(MSC),and post effluent treatment settled sludge(PTSS) were carried out.The optimum decontamination efficiency of 95%was obtained at 1 g/L MSC dosage.PW pH of 2.and rate constant of0.0001(L/g/s).Characterization results indicated that MS.MSC.and PTSS were of network structure,primitive lattice,and thermally stable.It could be concluded that MSC would be potential biomass for the treatment of produced water under the experimental conditions.     

Grain and malt quality properties of some improved Nigerian sorghum varieties

To determine their grain and malt quality properties, ten improved Nigerian sorghum varieties were subjected to several tests. The parameters that were tested included thousand corn weight, germinative energy, germinative capacity, water sensitivity, malting losses, hot and cold water extracts and free amino nitrogen (FAN). Results obtained showed variations among the sorghum varieties in most of the parameters assessed. While variety SK5912 was heaviest (40.25 g), variety Nafelen 6 had the lowest weight (22.45 g). For germinative capacity, variety KSV8 gave the highest value (97.0%), while variety ICSV400 gave the lowest value (90.5%). Variety KAT487 was the most water sensitive (5%), while four varieties simultaneously gave the lowest value. Boboje gave the lowest malting loss (13.77%), while the highest loss (37.74%) was given by White Kaura. For the extracts, variety SK5912 gave the highest value, as was the case also with FAN. Generally, there were significant differences across the different varieties of sorghum for malting loss, FAN, cold water extract and hot water extract at both p < 0.05 and p < 0.01. The results showed significant agreement with previous reports, with the key findings being that grain size mostly correlated positively with high expression of the critical malting parameters. Copyright © 2014 The Institute of Brewing & Distilling