Role of additives in fabrication of soy-based rigid polyurethane foam for structural and thermal insulation applications

Environmental concerns continue to pose the challenge to replace petroleum-based products with renewable ones completely or at least partially while maintaining comparable properties. Herein, rigid polyurethane (PU) foams were prepared using soy-based polyol for structural and thermal insulation applications. Cell size, density, thermal resistivity, and compression force deflection (CFD) values were evaluated and compared with that of petroleum-based PU foam Baydur 683. The roles of different additives, that is, catalyst, blowing agent, surfactants, and different functionalities of polyol on the properties of fabricated foam were also investigated. For this study, dibutyltin dilaurate was employed as catalyst and water as environment friendly blowing agent. Their competitive effect on density and cell size of the PU foams were evaluated. Five different silicone-based surfactants were employed to study the effect of surface tension on cell size of foam. It was also found that 5 g of surfactant per 100 g of polyol produced a foam with minimum surface tension and highest thermal resistivity (R value: 26.11 m²·K/W). However, CFD values were compromised for higher surfactant loading. Additionally, blending of 5 g of higher functionality soy-based polyol improved the CFD values to 328.19 kPa, which was comparable to that of petroleum-based foam Baydur 683.     

Alignment within the corporate IT unit: an analysis of software testing and development

Strategic alignment between an organization's business strategy/capabilities and those of its information technology (IT) unit is an extensively researched subject that addresses the issue of fit between business and technology strategies. A key gap in the literature is lack of recognition that underlying this macro level of alignment are other, more granular levels of alignment involving the interdependent subunits within the corporate IT unit. Given the critical interdependencies between development and testing subunits in software engineering, this paper focuses on an alignment model for ensuring that these two functions work together effectively. A development-testing alignment (DTA) model is described, and a case study investigating its value and application is presented. This DTA is decomposed into distinct components for the purposes of theoretical clarity and pragmatic application. The case study analysis uses the model to understand and interpret development-testing alignment in a Fortune 500 company. We found that the development and testing functions were significantly misaligned, and our model identified close to twenty specific aspects that needed to be considered to enhance alignment. These included changes in specificity of scope, governance, resource availability, competencies, and processes. Our analysis shows that the DTA model can be usefully applied for the purpose of understanding tactical alignment between subunits within a corporate IT unit. It also demonstrates that there is value in considering alignment as a dynamic, context-driven, social phenomenon as well as a useful interpretative lens for exploring organizational interactions and interdependencies.     

Dynamic coupled thermoelastic problems in micropolar theory—I

General solution of the dynamic micropolar coupled thermoelastic equations has been obtained for arbitrary distribution of body forces, body couples and heat sources in an infinite body by the use of Laplace-Fourier transforms. Short time solutions have been obtained for the cases of impulsive body force, body couple and heat source acting at a point. The corresponding classical coupled thermoelastic solutions have been derived by letting the parameter α approach zero. Some numerical results have been illustrated graphically.     

Ketorolac tromethamine in the maintenance of intraoperative mydriasis

BACKGROUND AND OBJECTIVE: Mydriatics and antiprostaglandins are routinely applied preoperatively to facilitate the aspiration of cortical material during extracapsular cataract surgery and to prevent intraoperative miosis. Unfortunately, the ideal antiprostaglandin has yet to be introduced. This study represents the first prospective, case-controlled, randomized, masked, clinical trial comparing the efficacy of oral ketorolac tromethamine (KT) with the efficacy of topical flurbiprofen sodium (FS) and a placebo (normal saline) in maintaining intraoperative mydriasis without adrenaline in the irrigation solution. PATIENTS AND METHODS: Sixty-three patients, undergoing extracapsular cataract extraction with posterior chamber intraocular lens implantation, were randomly divided into three equal groups. Group 1 received 20 mg of oral KT 2 hours prior to surgery, group 2 received 0.03% FS topical solution at the recommended dosage, and group 3 received topical normal saline in a regimen identical to that of group 2. Identical mydriatics were used in both groups. The patients' pupils were measured at five stages of surgery. RESULTS: The mean pupillary diameters at each surgical stage were greater in group 1 than in group 2; however, the difference was not statistically significant. The pupils in group 3 were significantly smaller than those of group 1 or group 2 (P < .05). No systemic toxicity to KT was observed. Moreover, the need for additional postoperative analgesics was significantly greater in groups 2 and 3. CONCLUSIONS: Oral KT is safe, convenient, and as effective as topical FS, and has the added advantage of reducing postoperative pain.     

The axisymmetric boussinesq problem of an initially stressed neo-hookean half-space for a punch of arbitrary profile

A solution of the axisymmetric Boussinesq problem for an initially stressed neo-Hookean half-space is obtained in the closed form, from which are deduced simple formulae for the depth of penetration of the tip of a rigid punch of arbitrary profile and the total load which must be applied to the punch to achieve this penetration. Simple closed form expressions are also deduced for the shape of the deformed surface outside the punch and the distribution of pressure under the punch. The corresponding results are obtained for cylindrical, conical, paraboloidal, ellipsoidal and spherical punch shapes.     

Diffraction of SH waves by a moving crack

Summary The problem of diffraction of anti-plane shear waves by a running crack of finite length is investigated analytically. Fourier transform method is used to solve the mixed boundary value problem which reduces to two pairs of dual integral equations. These dual integral equations are further reduced to a pair of Fredholm integral equations of the second kind. The iterative solution of the integral equations has been obtained for small wave number. The solution is used to calculate the dynamic stress intensity factor at the edge of the crack.With 2 Figures     

The axisymmetric Boussinesq problem for a semi-space in couple-stress theory

A solution of the axisymmetric Boussinesq problem is obtained, for a homogeneous and isotropic semi-space, from which are deduced simple formulae for the depth of penetration of the tip of a punch of arbitrary profile and the total load and torque which must be applied to the punch to achieve this penetration. Simple expressions are also deduced for the distribution of pressure and couple stress under the punch. Particular results are derived for cylindrical and conical punch shapes.     

Annular crack surrounding an elastic fibre in transversely isotropic elasticity

The axisymmetric problem of an infinitely long transversely isotropic elastic fibre perfectly bonded to a dissimilar transversely isotropic elastic matrix containing an annular crack is considered. The annular crack, surrounding the fibre, is subjected to prescribed longitudinal tension. A potential function approach is used to find the solution of the basic equations. The mixed boundary value problem is reduced to the solution of a singular integral equation, which is further reduced, by using Chebyshev polynomials, to a system of algebraic equations.