The ability to hit a target with precision and from a great distance has been reserved for the world’s superpowers. However, this resource is increasingly being threatened as drones with this long-range and precision...The ability to hit a target with precision and from a great distance has been reserved for the world’s superpowers. However, this resource is increasingly being threatened as drones with this long-range and precision capability are becoming more accessible to those who don’t have this strategic ability. This article starts with an analysis of the Iranian HESA Shahed 136 drone to discuss the latest innovations in low-cost long-range precision weapons, specifically the use of kamikaze drones and loitering munitions. This is an exploratory study that starts by discussing the notion of a kamikaze drone and then analyses the design options for the Shahed 136, to reflect on the future of this new type of weapon and its implications for the economic and political relationship between weapon and cost. The conclusion is that the HESA Shahed 136 revolutionizes the concept of precise long-range strikes, a function that until now was reserved for expensive and technologically demanding tactical missiles and aircraft, and which can now be carried out with cheap drones. This creates an arms race not only in producing the most technological and precise weaponry but also the least expensive.展开更多
Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the sta...Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.展开更多
A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discr...A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discriminate between varieties of olive oil. To achieve this task, Virgin Olive Oils (VOO) from two major Tunisian olive cultivars known as Chetoui and Chemlali were used. Spectral analysis showed a clear separation between these two VOO varieties. A one-way ANOVA attests that this discrimination is significant. The Principal Components Analyses (PCA) showed that the normalized fluorescence intensities are the good parameters for this discrimination. This observation strengthens the potential of our spectral parameters to perform reliable analysis.展开更多
Sliding contacts in laminar flow regimes have been investigated extensively in recent years. The results indicate the possibility to increase load carrying capacity in a slider bearing for more than 10% with the addit...Sliding contacts in laminar flow regimes have been investigated extensively in recent years. The results indicate the possibility to increase load carrying capacity in a slider bearing for more than 10% with the addition of dimples. Parametric studies have been performed to determine optimal size and position, with emphasis in the optimal shape and position of the dimple for an operating condition. In this article, the numerical analysis of a 2D textured slider bearing with a dimple is initially considered with an isothermal laminar fluid. Position, depth, width and convergence ratio are optimized, the results demonstrate the importance of the width and convergence ratio to increase load. Then, the numerical analysis of a 3D textured slider bearing with fore-region and extended channels at the outlet and on the sides of a pad is considered. The simulations are also carried out for a laminar isothermal flow. Three dimples are considered and their depth is optimized.展开更多
文摘The ability to hit a target with precision and from a great distance has been reserved for the world’s superpowers. However, this resource is increasingly being threatened as drones with this long-range and precision capability are becoming more accessible to those who don’t have this strategic ability. This article starts with an analysis of the Iranian HESA Shahed 136 drone to discuss the latest innovations in low-cost long-range precision weapons, specifically the use of kamikaze drones and loitering munitions. This is an exploratory study that starts by discussing the notion of a kamikaze drone and then analyses the design options for the Shahed 136, to reflect on the future of this new type of weapon and its implications for the economic and political relationship between weapon and cost. The conclusion is that the HESA Shahed 136 revolutionizes the concept of precise long-range strikes, a function that until now was reserved for expensive and technologically demanding tactical missiles and aircraft, and which can now be carried out with cheap drones. This creates an arms race not only in producing the most technological and precise weaponry but also the least expensive.
文摘Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.
文摘A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discriminate between varieties of olive oil. To achieve this task, Virgin Olive Oils (VOO) from two major Tunisian olive cultivars known as Chetoui and Chemlali were used. Spectral analysis showed a clear separation between these two VOO varieties. A one-way ANOVA attests that this discrimination is significant. The Principal Components Analyses (PCA) showed that the normalized fluorescence intensities are the good parameters for this discrimination. This observation strengthens the potential of our spectral parameters to perform reliable analysis.
文摘Sliding contacts in laminar flow regimes have been investigated extensively in recent years. The results indicate the possibility to increase load carrying capacity in a slider bearing for more than 10% with the addition of dimples. Parametric studies have been performed to determine optimal size and position, with emphasis in the optimal shape and position of the dimple for an operating condition. In this article, the numerical analysis of a 2D textured slider bearing with a dimple is initially considered with an isothermal laminar fluid. Position, depth, width and convergence ratio are optimized, the results demonstrate the importance of the width and convergence ratio to increase load. Then, the numerical analysis of a 3D textured slider bearing with fore-region and extended channels at the outlet and on the sides of a pad is considered. The simulations are also carried out for a laminar isothermal flow. Three dimples are considered and their depth is optimized.
