Vibration Reduction Performance of Damping-Enhanced Water-Lubricated Bearing Using Fluid-Saturated Perforated Slabs

As the first link element for the transmission of shaft vibration to the pedestal and even to the hull,water-lubricated bearing plays a key role in suppressing vibration.Although the porous structure is considered as one of the main methods for improving the wideband vibration and noise reduction performance of materials in many industrial fields,the studies in the field of water-lubricated bearing remain insufficient.To enhance vibration reduction performance,a fluid-saturated perforated slab is designed in this study,and via the establishment of a fluid-solid coupled vibration model,the influence law and impact levels were analyzed and verified by simulation and experiments.The results obtained verified that the total vibration amplitude of damping-enhanced stern bearing in the vertical direction was smaller than that of the normal stern bearing,and the reduction amplitude of the characteristic frequency agreed with the optimal value at approximately 0.1 of the volume fraction of the liquid phase when the solid-fluid phase was rubber–water.Additionally,the increase in fluid fraction did not enhance the damping effect,instead,it unexpectedly reduced the natural frequency of the raw material significantly.This research indicates that the design of the fluid-saturated perforated slab is effective in reducing the transmission of the vibration amplitude from the shaft,and presents the best volume fraction of the liquid phase.

Efficient Implementations of NTRU in Wireless Network

NTRU is a lattice-based public key cryptosystem featuring reasonably short, easily created keys, high speed, and low memory requirements, seems viable for wireless network. This paper presents two optimized designs based on the enhanced NTRU algorithm. One is a light-weight and fast NTRU core, it performs encryption only. This work has a gate-count of 1175 gates and a power consumption of 1.51 μW. It can finish the whole encryption process in 1498 μs at 500 kHz. As such, it is perfect for wireless sensor network. Another high-speed NTRU core is capable of both encryption and decryption, with delays of 16,064 μs and 128,010 μs in encryption and decryption respectively. Moreover, it consists of 25,758 equivalent gates and has a total power consumption of 59.2 μW (it will be reduced greatly if low power methods were adopted). This core is recommended to be used in base stations or servers in wireless network.

Efficient DPA Attacks on AES Hardware Implementations

This paper presents an effective way to enhance power analysis attacks on AES hardware implementations. The proposed attack adopts hamming difference of intermediate results as power mode. It arranges plaintext inputs to differentiate power traces to the maximal probability. A simulation-based AES ASIC implementation and experimental platform are built. Various power attacks are conducted on our AES hardware implementation. Unlike on software implementations, conventional power attacks on hardware implementations may not succeed or require more computations. However, the method we proposed effectively improves the success rate using acceptable number of power traces and fewer computations. Furthermore from experimental data, the correlation factor between the hamming distance of key guesses and the difference of DPA traces has the value 0.9233 to validate power model and attack results.

The Anti-Piracy Measure Using Encryption of Embedded Products May Mitigate the Security Strength

In this paper, firstly we describe the piracy problem of embedded products. Then we formulate the security features of anti-piracy embedded products. Finally we prove that the anti-piracy measure using encryption of embedded products may mitigate the security strength.

Review of the evolution and prevention of friction,wear,and noise for water-lubricated bearings used in ships

With the development of green tribology in the shipping industry,the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings.In terms of large-scale and high-speed ships,water-lubricated bearings with high performance are more strictly required.However,due to the lubricating medium,water-lubricated bearings have many problems such as friction,wear,vibration,noise,etc.This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism.Furthermore,the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle,test technology,friction and wear mechanism,and friction noise generation mechanism.The performance enhancement methods have been overviewed from structure optimization and material modification.Finally,the potential problems and the perspective of water-lubricated bearings are given in detail.

Asymmetric rotating array beams with free movement and revolution

We introduce a new class of partially coherent asymmetric array beams. When the beam propagates, the spectral density of each lobe and the corresponding degree of coherence have rotating behavior. Especially, not only can array-like lattices revolve arbitrarily, but also they can move freely by controlling transverse plane shifts. Furthermore, we have generated this kind of beam experimentally, and the experimental phenomena are consistent with the numerical simulation results. Such a rotating beam with free movement and revolution may broaden the way for optical applications. More importantly, it inspires further studies in the field of asymmetric coherence gratings and lattices.