A Precise RFID Indoor Localization System with Sensor Network Assistance

Indoor localization is very critical for medical care applications, e.g., the patient localization or tracking inside the building of the hospital. Traditional Radio Frequency Identification(RFID) technologies are very popular in this area since their cost is very low. In such technologies, each tag acts as the transmitter and the Radio Signal Strength Indicator(RSSI) information is measured from the readers. However, RSSI information suffers severely from the multi- path phenomenon. As a result, if in a very large area, the localization accuracy will be affected seriously. In order to solve this problem, we introduce Wireless Sensor Networks(WSNs) with only a few nodes, each of which acts as both transmitter and receiver. In such networks, the change of signal strength(referred as dynamic of RSSI) is leveraged to select a cluster of reference tags as candidates. Then the fi nal target location is estimated by using the RSSI relationships between the target tag and candidate reference tags. Thus, the localization accuracy and scalability are able to be improved. We proposed two algorithms, SA-LANDMARC, and COCKTAIL. Experiments show that the localization accuracy of the two algorithms can reach 0.7m and 0.45 m, respectively. Compared to most traditional Radio Frequency(RF)-based approaches, the localization accuracy is improved at least 50%.

The Research of Indoor Positioning Based on Visible Light Communication

The key techniques in indoor positioning based on visible light communication and the state of the art of this research were surveyed. First, the significance of indoor positioning based on visible light communication from two aspects of the limitations of current indoor positioning technology and the advantages of visible light communication was discussed; And then, the main four technology of indoor positioning based on visible light communication were summarized and the triangulation of RSS method and the principle of image positioning were introduced in detail; Next, the performance characteristics of various typical algorithms were compared and analyzed; In the end, several suggestions on future research of indoor positioning based on visible light communication were given.

室内CDMA用户定位方法研究

提出了一种基于最大似然(ML)法和最小二乘(LS)法的室内CDMA用户定位方法.根据CDMA信号模型和多径信道模型,估计室内用户信号到达已知位置的参考点的幅度衰减系数,然后根据室内传播损耗模型得到用户与参考点的相对距离,再利用参考点位置对用户进行定位.由于参考点可以为固定接收机或已被定位的室内用户,因此本定位方法还适用于多跳通信.本定位方法算法简单,但模拟结果表明却具有较高的定位精度.

Bilateral traumatic proximal humerus fractures managed by open reduction and internal fixation with locked plates

Fractures of the proximal humerus are uncommon in young patients.Although bilateral fracture of proximal humerus itself is rare,association with epilepsy and electrocution is frequent.Only one case of traumatic bilateral proximal humerus fracture has been reported in the literature.We report a rare case of bilateral traumatic displaced proximal humerus fractures in a 40 years old male patient,which was treated by means of open reduction and internal fixation with proximal humerus locked pates on both sides and obtained a good functional outcome.

Outcome of open reduction and internal fixation of intraarticular calcaneal fracture fixed with locking cal- caneal plate

Objective：Debate continues regarding the management of calcaneal fractures,between open reduction and internal fixation and closed treatment.Hence we aim at evaluating the radiological and functional outcomes of open reduction and internal fixation in displaced joint depression type of calcaneal fractures fixed with locking calcaneal plate.Methods：In this series,28 patients （26 unilateral and 2 bilateral） with joint depression type of calcaneal fractures as per Essex-Lopresti classification system were operated on with locking calcaneal plate within 3 weeks of injury.Patients were evaluated in terms of associated injuries and X-rays of anteroposterior,lateral and axial views of the calcaneum.CT scan was done to assess the amount ofcomminution and articular depression.Patients were followed up clinically and radiologically at least for 1 year.Radiological assessment was done by Bohler＇s angle and Gissane＇s angle along with measurement ofcalcaneal height and width.Functional outcome was assessed using the American Orthopaedics Foot and Ankle Society （AOFAS） scale.Results：At average follow-up of 14.5 months,average AOFAS score was 86.3 （range 66 to 97）,with 86% having excellent to good results and 2 （7.7%） and 1 （3.7%） having fair and poor results respectively.All patients had stable ankle joint with all having dorsiflexion and plantar flexion more than 30°.Average subtalar range of motion was 17°.The mean Bohler＇s angle,mean Gissane＇s angle,calcaneal height and width were 25.47°,121.3°,4.32 cm and 3.81cm respectively at final follow-up.Three patients had flap necrosis at incision site and one had superficial and deep infection.Subtalar arthritis was seen in 5 patients,whereas sural nerve hypoaesthesia in 1 patient.None of the patients had compartment syndrome,heel pad problems,peroneal tendinitis,reflex sympathetic dystropy or implant failure.Conclusion：Open reduction and internal fixation with locking calcaneal plate gives sound functional outcome,i.e.restoring anatomically reconstruction of height,width,Bohler＇s and Gissiane＇s angles of the calcaneum,and allowing early mobilization.

A distal-lock electromagnetic targeting device for intramedullary nailing： Suggestions and clinical experience

Purpose： To describe our clinical experience with a system named SureShorTM Distal Targeting （Smith ＆ Nephew, Memphis, USA） based on magnetic field presence and discuss our suggestions on this technique. Methods： We analysed prospectively 47 patients affected by humeral, tibial or femoral fractures, treated in our institution during a 3-year period of time （August 2010 to September 2013）. We considered the following parameters： the time to set up, the time to position a single screw, the effectiveness of the system （drilling ad screwing）, the irradiation exposure time during distal locking procedure and surgical complications. Results： A total number of 96 screws were inserted. The mean preparation time of the device was 5.1 min _＋ 2 min （range 3 10 min）. The mean time for single screw targeting was 5.8 min ± 2.3 min （range 4-18 min）. No major complications occurred. Only a few locking procedures were needed to be practiced in order to obtain the required expertise with this targeting device. Conclusion： According to our results, this device is reliable and valid whenever the correct technique is followed. It is also user friendly, exposes to lower radiation and needs less surgical time compared to relative data from the literature. However, the surgeon should always be aware of how to use the free hand technique in case of malfunctioning of the system.