Semi-static method

The method derives its name from Wilhelmy who long ago described the detachment of a thin glass plate. Although nowadays static, or semi-static methods are preferred, the name of Wilhelmy remains associated with these techniques. This static Wilhelmy approach stems from Dognon and Abribat ), who also introduced roughened platinum plates to improve wetting. Such plates remain popular. 

International Organization for Standardization (ISO) (1996c) Water Quality - Determination of the Acute Lethal Toxicity of Substances to a Freshwater Fish (Brachydanio rerio Hamilton-Buchanan (Teleostei, Cyprinidae) - Part 2 Semi-static Method, ISO 7346-2. ISO, Paris. 

As compared to static methods, the semi-static methods for surface tension measurement are based on achieving a metastable equilibrium, and focused mainly on investigating the conditions under which the system loses that equilibrium. 

The threshold of the equilibrium state can generally be reached slowly, and thus the surface tension values obtained by semi-static methods closely resemble those obtained by static ones. The rate of approaching the equilibrium state should be optimized in each system, in order to avoid lengthy measurements and to obtain surface tension values as close to the equilibrium ones as possible. Among the most common semi-static methods are the method of maximum pressure, the du Noiiy ring method and the drop-weight method. 

The low rate at which equilibrium between the adsorption layer and the bulk is established is typical for high molecular weight surface active substances for which the surface tension gradually decreases with time. The measurement of the surface tension by static and semi-static methods (see Chapter I, 4) as a function of time during the formation of adsorption layers allows one to retrieve information on the kinetics of adsorption phenomena [11,12]. 

Lindh Pershak (Ref 5) describe a semi-empirical method foir predicting the effect of weld defects on static and fatigue properties... 

The specific surface free energy and the surface tension, a, numerically equal to it can be accurately determined at the gas-liquid and liquid-liquid interfaces. In this section we describe the general principles on which various methods for the determination of surface tension are based. In general, these methods can be classified as static, semi-static and dynamic. This classification, however, may be further extended with the dynamic versions of some methods listed below as static or semi-static exist. Extensive review of the methods used to determine the surface tension is given in [6,16-18]. 

This description of quantum mechanical methods for computing (hyper)polarizabilities demonstrates why, nowada, the determination of hyperpolarizabilities of systems containing hundreds of atoms can, at best, be achieved by adopting, for obvious computational reasons, semi-empirical schemes. In this study, the evaluation of the static and dynamic polarizabilities and first hyperpolaiizabilities was carried out at die Time-Dependent Hartree-Fock (TDOT) [39] level with the AMI [50] Hamiltonian. The dipole moments were also evaluated using the AMI scheme. The reliability of the semi-empirical AMI calculations was addressed in two ways. For small and medium-size push-pull polyenes, the TDHF/AMl approach was compared to Hartree-Fock and post Hartree-Fock [51] calculations of die static and dynamic longitudinal first hyperpolarizability. Except near resonance, the TDHF/AMl scheme was shown to perform appreciably better than the ab initio TDHF scheme. Then, the static electronic first hyperpolaiizabilities of the MNA molecule and dimer have been calculated [15] with various ab initio schemes and compared to the AMI results. In particular, the inclusion of electron correlation at the MP2 level leads to an increase of Paaa by about 50% with respect to the CPHF approach, similar to the effect calculated by Sim et al. [52] for the longitudinal p tensor component of p-nitroaniline. The use of AMI Hamiltonian predicts a p aa value that is smaller than the correlated MP2/6-31G result but larger than any of the CPHF ones, which results fi-om the implicit treatment of correlation effects, characteristic of die semi-empirical methods. This comparison confirms that a part of die electron... 

This Rapid-Static (or pseudo-kinematic) technique is a further development of the kinematic technique describe above. The method is operationally similar to the stop-and-go (semi-kinematic) method, except that it does not require that lock be maintained on the satellite signals when moving between successive stations. 

The use of static analysis, dynamic analysis or failure analysis to form all equivalence classes (blackbox test data), which can reduce number of test cases. Also the use of structured design or semi-formal methods or statistical evidence can permit a reduced depth and number of test cases. 

Wrist affected with Rheumatoid Arthritis was commonly associated with carpal bones instability. In addition, stability of the wrist arthroplasty was still arguable due to some clinical reported the failure of the wrist arthroplasty due to weak fixation in which lead to instability. One of the suggested methods to enhance the fixation was to use bone graft. It was clearly observed in the results that the displacement of the bones as well as implants in the model fixed with bone graft is low. Since this study was established under semi-static condition, the low displacement significantly indicated the stability of the implant fixation. Thus, the fixation with bone graft found to be relatively... 

This method is valid only in the static field limit (zero frequency), which is a weakness. However, recent advances of a derived procedure (Coupled Perturbed Hartree-Fock) permit the frequency dependence of hyperpolarizabilities to be computed. The FF method mainly uses MNDO (modified neglect of diatomic differential overlap) semi-empirical algorithm and the associated parametrizations of AM-1 and PM-3, which are readily available in the popular MOPAC software package. ... 

---