Aspects of the mechanics of driving nails into wood

For nail driving, some aspects of the effect on penetration of the hammer mass, the speed at impact, the nail size and section shape and the driving direction in relation to the wood grain are reported.A 6 in. long, 0·236 in. dia., round nail was strain gauged to show how the strain in the nail varies with time during an impact.An analysis, which reasonably accounts for the experimental results, is developed for predicting the strain pulse in the nail, the amount of penetration by the nail and its time under strain.Maintaining the same kinetic energy input at each blow, it is found that the larger the initial penetration, the smaller is the further penetration.The effect on penetration depth of the material backing to the piece of wood is reported.The variation of the Euler buckling load with the nail penetration for a specific type of wood and nail dimensions is given.     

Optimal linear approximation in project compression

When the cost of reducing the duration of activities is convex and nonlinear, it may be advisable (to reduce the computing burden) to seek a “satisficing” answer, in which the project is compressed to a desired completion time with a prespecified tolerable relative error. We treat the problem of constructing the optimal first degree interpolating linear spline that guarantees such maximal error and consider various possible refinements.     

Sugars and amino acids in dried Iraqi figs

The sugars in the dried Iraqi figs (Wazeri Variety) were examined by paper chromatographic analysis. Glucose comprised (34.30%), and fructose (31.20%) together with (7.82 %) of the fruit. Polysaccharides were found to be arabogalactans. Iron, calcium and phosphorus were found to be 14, 145 and 150 mg per 100 g dry weight respectively. Hydrolysis showed the presence of all the essential amino acids with adequate lysin and sulphur amino acids but relatively little tryptophan.     

Copper complexes of Di-, Tri- and hexapeptides containing N2, N4-diaminobutyric acid

Sixteen copper complexes of di-, tri- and hexapeptides containing N², N⁴-diaminobutyric acid are studied spectrophotometrically. The λ_max, and colour of the complex is independent of the sequence of the amino acid in any of these peptides. The N⁴-amino group of the A₂bu-residues do not participate in complex formation. However, the hydrazide group of di- and tripeptide hydrazides participates in complex formation.     

Flow and heat transfer over shallow cavities

The flow over a shallow cavity heated with constant heat flux form the bottom side has been studied experimentally and numerically. In the experimental part, pressure coefficient and Nusselt number have been measured along the cavity floor. In the numerical simulation, the conservation equations of mass, momentum, and energy have been solved. The standard k–? turbulence model is used to account for the turbulent fluctuations. In both experimental and numerical part, the effect of changing cavity aspect ratio and Reynolds number has been studied. It is found that, a single elongated eddy has been formed for aspect ratio lower than 7. As the aspect ratio increases the flow impinges with the cavity floor creating two eddies, one beside the upstream cavity side and the second beside the downstream cavity side. Local Nusselt number along the cavity floor is affected mainly by the flow structure inside the cavity and the average Nusselt number has increased with increasing the aspect ratio up to 10 and with increasing Reynolds number. A correlation for the average Nusselt number, as a function of Reynolds number and cavity aspect ratio, is developed.     

Artificial Neural Network modeling of a hydrogen dual fueled diesel engine characteristics: An experiment approach

The rapid growth of vehicular pollution; mostly running on the diesel engine, emissions emerging are the concerns of the day. Owing to clean burn characteristics features, Hydrogen (H₂) as a fuel is the paradigm of the researcher. Extensive research presented in the literature on H₂ dual fueled diesel engine reveals, the significant role of H₂ in reducing emissions and enhancing the performance of a dual fueled diesel engine. With meager qualitative experiment data, the feasibility to develop an efficient Artificial Neural Network (ANN) model is investigated, the developed model can be utilized as a tool to investigate the H₂ dual fueled diesel engine further. In the process of developing an ANN model, engine load and H₂ flow rate are varied to register performance and emission characteristics. The creditability of the experiment is ascertained with uncertainty analysis of measurable and computed parameters. Leave-out-one method is adopted with 16 data sets; seven training algorithms are explored with eight transfer function combinations to evolve a competent ANN model. The efficacy of the developed model is adjudged with standard benchmark statistic indices. ANN model trained with Broyden, Fletcher, Goldfarb, & Shanno (BFGS) quasi-Newton backpropagation (trainbfg) stand out the best among other algorithms with regression coefficient ranging between 0.9869 and 0.9996.     

Cold Shock and Various Extenders Effects on Physical and Chemical Characteristics of Ram Sperms

The protective effect of egg yolk citrate, egg yolk skimmed milk, and egg yolk lactose extenders on the sperm cell against freezing injury was studied using Ossimi and Rahmani rams. Advanced motility, dead and coiled tail percentages of fresh spermatozoa did not differ significantly between the two breeds. Freezing caused a highly significant increase in dead and coiled tail percentages of spermatozoa diluted with various extenders. Unsaponifiable matter of fresh spermatozoa of both breeds contained various hydrocarbons and sterols with C 26, C 24 and cholesterol being the basic compounds. The unsaponifiables distribution could be used to characterize the spermatozoal origin. Changes in total sterols/total hydrocarbons ratios of the unsaponifiables were occurred after freezing of both breeds using the three extenders. Cholesterol content of fresh spermatozoa and the changes in physical properties of spermatozoa of both breeds indicated that the freezability of Ossimi semen was better than that of Rahmani. Also, the changes occurred in physical properties and total sterols/total hydrocarbons ratios showed that egg yolk lactose extender was better than egg yolk skimmed milk and egg yolk citrate extenders for sperm protection against freezing injury.