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Clinical and radiological signs are named after natural signs. This chapter summarizes the imaging features and theories regarding the pathophysiology of various relatively common head-and-neck abnormalities. Understanding of MRI sequences is essential for the correct and reliable interpretation of lesions in the head and neck, as well as careful selection of MRI protocols based on relevant clinical information.

With the rapid development of smart grid, collaborative communication among many subsystems of power system is becoming more and more frequent. With the progress of communication technology, distribution network communication network is gradually developing towards the direction of heterogeneous network integration. Traditional network management system based on equipment status monitoring cannot fully reflect the operation status of communication network, so this paper studies the network and service monitoring technology of intelligent distribution network communication system. Firstly, the system services of the distribution network communication system are analyzed from the typical business requirements. The traffic requirements, security requirements and real-time requirements are introduced respectively. The flow measurement technology based on passive measurement and the network quality monitoring technology based on active measurement are designed. According to different service requirements, different service detection technologies can be provided to monitor the quality of distribution network service communication network in real time.

Increasing the coverage rate of ultrasonic path to flow field is helpful to improve measurement results’ accuracy of transit-time ultrasonic flowmeters while asymmetric flow or turbulence exists. In this paper, a 3D isosceles triangular ultrasonic path is presented considering the width of the ultrasonic signal and the maximum coverage rate of the ultrasonic path to flow field. To evaluate the feasibility and effectiveness of the path proposed, computational fluid dynamics simulations of three pipeline configurations, including straight pipeline, single elbow, and contracted pipeline upstream ultrasonic flowmeter $3D_{\rm pipe}$ (diameter of pipeline, $D_{\rm pipe})$ , $5D_{\rm pipe}$ , or $8D_{\rm pipe}$ long are performed. In particular, inlet velocity of flow ranges from 0.1 to 10 m/s. Meanwhile, control simulation of U-type ultrasonic path is discussed to verify the effect of coverage rate of ultrasonic path to flow field on measurement results. It is shown that the proposed 3D isosceles triangular ultrasonic path, whose coverage rate is 54%, does well in improving the stability and accuracy of measurement results while pipeline configuration upstream flowmeter changes.

Aim: The clinical value of FibroScan in evaluation of hepatic fibrosis was assessed in Chinese patients with nonalcoholic fatty liver disease (NAFLD). Methods: Liver stiffness and other NAFLD related variables were measured in NAFLD patients with either elevated or normal hyaluronic acid (HA) levels, and in healthy volunteers respectively. Moreover, hepatic fibrosis rat model was used for the correlation analysis between the measured liver elasticity and its corresponding pathological changes. Results: The severity of NAFLD in patients was positively correlated with both HA level and FibroScan values suggesting that fibrosis occured along with the progression of NAFLD. Interestingly, the FibroScan value was found to change at an earlier stage of the disease than that of HA level. The mean liver elasticity in the sampling volume of the region of interest in experimental rats, which were subject to the induction of liver fibrosis using peritoneal injection of carbon tetrachloride (CCl4) for 6 or 9 weeks respectively, was measured using Fibroscan. The examination of pathological changes of these experimental rats demonstrated the positive correlation of the measured elasticity values with the extent (severity) of the corresponding pathological changes in the rats of 6 weeks post induction of liver fibrosis with a moderate liver fibrosis, or 9 weeks with a severe liver fibrosis. The average liver stiffness for the normal liver (S0) was 4.51 ± 0.82 kPa, for moderate liver fibrosis (S2) was 6.91 ± 1.32 kPa, and for severe liver fibrosis (S3) 9.62 ± 1.82 kPa. Conclusion: FibroScan can be used to objectively and quantitatively identify the trend in the changing stiffness of the liver and noninvasively detect the development of liver fibrosis.

Taking ship-bridge collision as an example, how the wave propagation and the dynamic behavior of materials influence the impact force and energy transformation are studied from the impact dynamics viewpoint. By using a new flexible, energy-dissipating crashworthy device developed by the authors, both the impact force and energy transformed can be markedly reduced, which is much conductive to protect both bridge and ship.

It is helpful to improve the accuracy of the flying-start-stop liquid flow calibration facilities used to calibrate different types of flowmeters by studying and decreasing the flow diverter timing error. In this paper, a transforming relationship model of diverting flow error and timing error is proposed to reveal the principle of the timing error. Meanwhile, a same directional diverter based on the transforming relationship model is also proposed, which has the following advantages: a small timing error, a high repeatability accuracy, no need to adjust the trigger position, easy to implement ISO4185 calibration test, a wide range of working flow rates, easy to be manufactured, and a good portability. To verify the advantageous characteristics of the same directional diverter, the performance comparing experiments of the same directional diverter and the traditional diverter under different flow rates, trigger positions, and diverter moving velocities are proposed. The results show that the timing error of the same directional diverter has no relationship with trigger position and has low sensitivity in both flow rate and the diverter moving velocity. While the diverter moving velocity is 0.1 m/s, the absolute value of the timing error of the same directional diverter just varies from 0.251 to 1.473 ms, which is much smaller than the traditional diverter’s (varies from 9.940 to 532.302 ms). The uncertainty caused by the timing error and the total uncertainty of measuring time of the same directional diverter vary from 0.000454% to 0.000883% and 0.000529% to 0.000924%, respectively.

The impact force during ship-bridge collision based on quasi-static mechanics and impact dynamic are analyzed and compared. How the wave propagation and the dynamic behavior of materials influence the impact force are studied from the view-point of stress wave propagation.