Cyclic representations of the periodic Temperley Lieb algebra, complex Virasoro representations and stochastic processes

An $N$ ${L} \choose {L/2}$-dimensional representation of the periodic Temperley-Lieb algebra $TL_L(x)$ is presented. It is also a representation of the cyclic group $Z_N$. We choose $x = 1$ and define a Hamiltonian as a sum of the generators of the algebra acting in this representation. This Hamiltonian gives the time evolution operator of a stochastic process. In the finite-size scaling limit, the spectrum of the Hamiltonian contains representations of the Virasoro algebra with complex highest weights. The $N = 3$ case is discussed in detail. One discusses shortly the consequences of the existence of complex Virasoro representations on the physical properties of the systems.Comment: 5 pages, 6 figure

Verification of Properties of Concrete Reinforcement Bars: Nigeria as Case Study

An investigation was conducted into the level of conformance of ribbed steel bars used in Nigeria's structural concrete practice to relevant international and local provisions. In this research, all bars imported into Nigeria from member countries of ISO as well as bars marked with the identity of the local producing mill are classified as steel of recognizable origin. On the other hand, bars imported from ISO non-member countries as well as those without identifying mark of the producing works are classified as steel of non-recognizable origin. The results of the investigation showed that steel of recognizable origin satisfy both local and ISO requirements for strength and ductility. On the other hand, steel of non-recognizable origin failed to satisfy the above requirements for high-yield ribbed bars but satisfies the local specifications if used as mild steel. Keywords: Ribbed steel bar, Strength, Ductility, Recognizable, Tensile testAfrican Research Review Vol. 2 (2) 2008 pp. 234-25

Modeling, Behaviour Prediction, and Control – Tripartite Essentials of Contemporary Structural Engineering Education

Computers have today permeated every sphere of human endeavour and structural engineering is no exception. Multiply-hyperstatic structures which relatively recently took teams of structural engineers several months to analyse can now be elegantly analysed in a matter of seconds using computers equipped with readily available and userfriendly analysis/design software. This paper examined the contemporary structural engineer and the shift his education must accommodate in order for his relevance not to diminish in the face of the new realities posed by the computer. The results of the study showed that there should now be an orientation shift in the education of the structural engineer. More time should now be apportioned to learning the intricacies of structural modeling, understanding structural behaviour, and controlling same to achieve the desired design objective. On the other hand, although the classical analysis methods should still be taught, the time allocated to them should now be significantly reduced. Examples were given for quantitative illustration of the issues involved. In conclusion, the paper argued that the above three essentials should form the cornerstone of modern structural engineering education. Keywords: Analysis, Design, Modeling, Structural Behaviour, Control, Approximate Methods. African Research Review Vol. 2 (3) 2008: pp. 1-2

Mechanical Performance of Recycled Aggregate Concrete Containing Lathe Waste Steel Fibre

The increasing demand, diminishing supplies, and growing pressure on natural resources have necessitated recycling and reusing waste. Several kinds of research have been done on the reuse and recycling of debris from building projects. Thus, with a view to the reuse of waste materials, the elimination of environmental contamination, the reduction of overhead costs of concrete, and the extension of the service life of concrete structures, this research aimed to study the feasibility of utilizing recycled concrete aggregate (RCA) with constant inclusion of waste steel fibre (LWSF) in concrete by evaluating its workability, compressive and splitting tensile strengths. A concrete mix ratio of 1:2:4 by weight of cement, sand, and granite was adopted with a water-cement ratio of 0.45. Five different concrete mixes were prepared in this study; one normal aggregate concrete (NAC) and four (4) other mixes with 25%, 50%, 75%, and 100% recycled aggregate content with a constant 1.5% addition of LWSF. The result of workability shows a reduction with an increase in the percentage replacement level. The recycled aggregate concrete (RAC) was characterized by lower compressive strength as compared with the NAC. When the replacement ratio increased from 25% to 50%, a significant reduction of about 14% and 30% were observed in the compressive strength at 7-days, but at 28-days slight increase in the compressive strength was observed. Also, a decrease in splitting tensile strength as the percentage replacement of crushed granite (CG) with RCA is increased was observed. Overall, the findings showed that the RAC-containing LWSF is environmentally sustainable and would significantly reduce the global greenhouse impact and building materials' overall quality. Keywords: Recycled concrete, lathe waste, steel fibre, compressive strength, tensile strengt

LINEAMENT DENSITY INFORMATION EXTRACTION USING DEM SRTM DATA TO PREDICT THE MINERAL POTENTIAL ZONES

Utilization of remote sensing in geology is based on some identification of main parameters. They were the relief or morphology, flow patterns, and lineament. So it was necessary to study extraction method based on those parameters. This study aimed to obtain lineament density zone in the Geumpang area, Aceh, associated with mineral resource potential. Information of lineament density using remote sensing data was expected to help solve the problems that arised in the activities of early exploration, the difficulty of finding the prospect areas, so that the activities of pre-exploration always required a wide area and required a long time to determine the location of mineral prospect areas, it would have a direct impact on the financial of exploration activities. The used data was Landsat 8 and DEM SRTM of 30 m. The used method was processing of shaded relief on DEM data with the azimuth angle 0o, 45o, 90o, and 135o, then the result of hill shade process was done overlay, so DEM seen from all different azimuth angles. The results of the overlay were processed using the algorithm LINE with parameters such as the radius of the filter in pixels (RADI) 60, the threshold for edge gradient (GTHR) 120, the threshold for the curve length (LTHR) 100, the threshold for line fitting error (FTHR) 3, threshold for angular (ATHR) 30, and the threshold for linking distance (DTHR) 100. Vector lineament data from LINE algorithm process then performed density analysis to obtain lineament density zoning. Results from the study showed that the area has a high density lineament associated with mineral potency, so it was useful for exploration activities to minimize the survey area

Exploring Antecedents & Consequences Of Customer Satisfaction With Smartphones: Implications For CRM

Customers of smartphones spend most of their waking time using them, as they have become the most innovative electronic devices. As the time spent on smartphones increases, the customer’s dependence on smartphones also increases. Therefore smartphones are more than telecommunication devices to customers. This paper examines factors (i.e., antecedents) affecting smartphone customer satisfaction and factors (i.e., consequences) arising from smartphone customer satisfaction. In particular, this study explores how the level of customer satisfaction affects loyalty, brand image, corporate image and country of origin. This study involved an online survey and applied t-test, factor, and regression analyses. The results provide managerial and theoretical implications for satisfaction and customer relationship management.

Synthesis of Emulsifier from Refined Bleached Deodorized Palm Stearin by Chemical Glycerolysis in Stirred Tank Reactor

Emulsifiers are widely used in the food and beverage industry, especially the mixture of mono- and diacylglycerol. They are produced from glycerolysis reaction using chemical catalysts because of fast reaction time, high conversion of reactants and low cost. Palm stearin is abundant and less utilized. Therefore, palm stearin is used as raw material for the synthesis of emulsifiers. The goal of this project was obtained emulsifier containing high concentrations of mono- and diacylglycerol. Synthesis of emulsifier was conducted with reaction time (1 h to 12 h), catalyst concentration (1 %, 2 %, 3 %, and 4 %) (w/w) and addition of molecular sieve (12 % (w/w) and without as control). Furthermore, products were fractionated at various temperatures (40 ∘C, 30 ∘C, 20 ∘C, and 10 ∘C). These results suggest that the best conditions for the synthesis of mono- and diacylglycerol from palm stearin using NaOH catalyst in Batch stirred Tank Reactor are NaOH concentration 3 % (w/w), reaction time 6 h, molecular sieves 12 % (w/w), reaction temperature 90 ∘C, addition of tert-butanol as solvent 2 mL ⋅ g −1 of oil, palm stearin: glycerol molar ratio (1 : 5), the speed of the stirrer of 400 rpm. The fractionation temperature is 30 ∘C with product yield is 61.43 % which contains 91.00 % ± 2.50 % and 9.00 % ± 2.50 % of monoand diacylglycerol, respectively. Characteristic of emulsifiers are emulsion capacity 95.55 % ± 0.71 %, emulsion stability 90.44 % ± 1.24 %, HLB value 10.25 ± 0.44, melting point 62.67 ∘C ± 2.52 ∘C to 70.33 ∘C ± 0.58 ∘C and type of emulsion is oil in water (o/w). Keywords: Emulsifier, Glycerolysis, Mono- and diacylglycerol, NaOH, Palm steari

MODE OF COLLAPSE OF SQUARE SINGLE PANEL REINFORCED CONCRETE SPACE- FRAMED STRUCTURES WITH RIGID BEAM-COLUMN JOINTS

The behavior of the structural elements of a space-framed structure depends on their support conditions. These support conditions can be hinged or rigid for beam-column joints, while for slab these support conditions can be simply supported on walls that are not monolithically constructed together, simply supported on beams that are monolithically constructed together and, can be freely supported on one, two or three edges. This paper studies the mode of collapse of collapse of a single-paneled reinforced concrete space-framed structure with rigid beam-column joints. Five models were investigated for the interactive behavior of slabs, beams and columns. The models were loaded directly till collapse. The estimated and actual collapse loads of the five models were compared. The estimated collapse load for the slab was 35 kN/m2. Also, the numerical estimate of the collapse load for the beam was 10.2kN/m (with an equivalent slab load of 40.8kN/m2), while the shear capacity at the beam-column joints was estimated to be 19.14 kN. The mode of collapse for all the five models was by shear failure at the beam-column joints at an average shear force of 7.13 kN as against the estimated shear capacities of 19.14 kN,  showing that the existing formulae for predicting shear capacity of beam-column joints gave an overestimated value of joint shear capacity up to about 168%. It was found that the space framed models failed by shearing at the beam-column joints, and that the estimated shear capacity was greater than the shear force at collapse.  http://dx.doi.org/10.4314/njt.v35i1.

Forest Product Industry and Engineered Wood Products: The Nigerian Experience

The forest product industry in Nigeria is barely surviving rather than thriving. Faced with a lot of challenges, the industry has witnessed the closure of many wood processing industries while a few are operating at low capacity. This paper examines engineered wood products and the outlook on wood and wood products in Nigeria. It discusses some of the challenges that have inhibited the growth of the industry and provides recommendations for reinventing the industry through development of modern value-added wood products for sustainable building construction. Keywords: Collaboration; Engineered wood products; Forestry product industry; Glulam; Sustainability

Evaluation of Physical and Mechanical Properties of Selected Wood Species obtained from Saw Mills in Akure, Nigeria

The strength and sorption properties of selected wood species obtained from saw mills in Akure Nigeria were investigated based on key index properties such as density, bending strength and dimensional stability using appropriate standard experimental techniques. Data obtained from the experimental investigation revealed that the wood species ranged from low density 442.8 kg/m3 for Terminalia superba (Afara), through medium density 464 kg/m3 and 552.8 kg/m3 for Pycnanthus angolensis (Akomu) and Gmelina arborea (Gmelina) respectively, to high density 635.7kg/m3 and 678.2 kg/m3 for Milicia excelsa (Iroko) and Stereospermum acuminatissimum (Omo cedar) respectively. The bending strength values obtained qualified the wood species classification into low bending strength (25 N/mm2 – 75 N/mm2 ) for Afara, Akomu and Gmelina and the medium static bending strength in the range (75 N/mm2 – 125 N/mm2) for Iroko and Omo cedar. Furthermore, results of volumetric shrinkage and swelling are 7.21%: 5.04%, 7.75%: 5.26% and 7.84%: 6.69% for Afara, Akomu and Gmelina respectively while Iroko and Omo cedar recorded 10.95%: 7.84% and 11.08%: 11.08%. These updated results could be useful for wood selection for building construction application; for structural members in roofing, posts and beams