ABSTRACT
In this paper, a Ka-band coaxial transit time oscillator (TTO) with internal extraction is proposed. Particle-in-cell simulation of this oscillator is performed to obtain results as follows: under the conditions of a diode voltage of 459 kV, current of 3.9 kA, and guiding magnetic field of 0.5 T, microwaves with an output power of 0.75 GW and a frequency of 31.4 GHz can be achieved with an efficiency of 42% and a saturation time of nearly 25 ns. Moreover, the asymmetric mode competition is suppressed in the preliminary experiments. The study of a Ka-band TTO aims to extend the working frequency of high power microwave sources to a higher level. Such a device has three merits. First, it implements high power and high efficiency. Second, the internal extraction of the microwave output decreases the over-mode ratio in the microwave extraction region. Third, the over-mode ratio of the internal extraction is smaller compared with the external extraction, which can effectively suppress asymmetric mode competition.
ABSTRACT
OBJECTIVE: To explore the minimally invasive treatment for fresh acromioclavicular dislocation and the distal clavicle fracture. METHODS: Thirty skeletons of human shoulder were measured and compared, and the normal data on healthy people were measured with the help of ultrasound-guided. So the invasion point was located at the cross between subclavian axis and the line from coracoid tip to apophysis behind cone ligament node. From January 2001 to January 2010, 127 patients with fresh acromioclavicular dislocation and distal clavicle fracture were treated with minimally invasive internal fixation after locating the invasive point at the body surface. Among the patients, 97 patients were male and 30 patients were female, ranging in age from 19 to 56 years, with an average of 43 years. According to Rockwood classification, among 93 patients with fresh acromioclavicular dislocation, 67 patients were type III, 11 patients were type IV and 15 patients were type V. All the 34 patients with distal clavicle fractures were associated with coracoclavicular ligament broken. The duration from injury to operation ranged from 1 to 8 days. The therapeutic effects were evaluated by using the of shoulder scoring system, University of California (UCLA). RESULTS: After the minimally invasive treatment, all the patients had completely reduction at early time. One hundred and thirteen patients were followed up,and the duration ranged from 13 to 15 months,averaged 14 months. Nine patients had screw loose slightly within 30 days, but the reductions and functions were acceptable. Seven patients had complications of frozen shoulder and recovered in 6 months. The average UCLA shoulder score was (32.0 +/- 4.7), and 87 patients got an excellent result, 20 good and 6 fair. CONCLUSION: This minimally invasive treatment has advantages such as little trauma and low cost, which is worthy of clinical applications.
