Development time, survival, reproduction, and sex ratio were determined for the predatory mite Neoseiulus longispinosus (Evans) at six constant temperatures (20, 25, 27.5, 30, 32.5 and 35 oC) reared on citrus red spider mite Panonychus citri (McGregor). No predatory mite reached adulthood at 35oC. All female and male immature stages of N. longispinosus developed significantly faster as the temperature increased from 20to 30 oC, but development slowed down as the temperature exceeded 30 oC. The mean total developmental time of females was longest at 20 °C (9.73 days), followed by 25oC (5.67 days), 27.5oC (4.46 days), and 32.5 oC (4.55 days) and was shortest at 30oC (3.69 days). The oviposition rate and lifetime fecundity were highest at 27.5 oC (2.80 eggs/female/day and 43.76 eggs/female, respectively) and lowest at 20 oC (0.78 eggs/female/day and 21.64 eggs/female, respectively). However, temperature had no influence on the sex ratio of offspring with the proportion of females ranging from 0.62 to 0.65. The intrinsic rate of increase (r) of N. longispinosus averaged 0.323, 0.303, 0.267, 0.189 and 0.107 females female−1 day−1 at 30, 27.5, 32.5, 25, and 20°C, respectively. These values suggested that the most optimal temperatures for the population growth of N. longispinosus were between 27.5 and 30oC.
The receptance function has been studied and applied widely since it interrelates the harmonic excitation and the response of a structure in the frequency domain. This paper presents the derivation of the exact receptance function of continuous cracked beams and its application for crack detection. The receptance curvature is defined as the second derivative of the receptance. The influence of the crack on the receptance and receptance curvature is investigated. It is concluded that when there are cracks the receptance curvature has sharp changes at the crack positions. This can be applied for the crack detection purpose. In this paper, the numerical simulations are provided.
In this paper, numerical and experimental studies for crack detection of structures using "element stiffness index distribution" are presented. The element stiffness index distribution is defined as a vector of norms of sub-matrices corresponding to element stiffness matrices calculated from the reconstructed global stiffness matrix of the beam. When there is a crack at an element, the element stiffness index of that element will be changed. By inspecting the change in the element stiffness index distribution, the crack can be detected. A significant peak in the element stiffness index distribution is the indicator of the crack existence. The crack location is determined by the location of the peak and the crack depth can be determined from the height of the peak. The global stiffness matrix is calculated from the measured frequency response functions instead of mode shapes to avoid limitations of the mode shape-based methods for crack detection. Numerical simulation results for the cases of beam-like structures are provided. The experiment is carried out to justify the efficiency of the proposed method.
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