On the unimodality of independence polynomials of some graphs

In this paper we study unimodality problems for the independence polynomial of a graph, including unimodality, log-concavity and reality of zeros. We establish recurrence relations and give factorizations of independence polynomials for certain classes of graphs. As applications we settle some unimodality conjectures and problems.Comment: 17 pages, to appear in European Journal of Combinatoric

Electro-thermal design and optimization of high-specific-power slotless PM machine for aircraft applications

A 1 MW high-frequency air-core permanent-magnet (PM) motor, with power density over 13 kW/kg (8 hp/lb) and efficiency over 96\%, is proposed for NASA hybrid-electric aircraft application. In order to maximize power density of the proposed motor topology, a large-scale multi-physics optimization, which is not favorable for current electrical machine software, is needed to obtain the best design candidates, which is not favorable for current electrical machine software. Therefore, developing electromagnetic (EM) and thermal analytical methods with computational efficiency and satisfactory accuracy is a key enabling factor for future multi-physics optimization of motor power density. This dissertation summarizes the efforts of developing an electro-thermal analysis and optimization scheme of the proposed motor for aircraft applications. Component hardware tests including windage loss, fan performance, full-scale stator temperature and litz-wire were conducted to validate the proposed prediction methods and provide calibrations in the motor design analysis. Furthermore, slotless litz wire winding geometry and strand size are optimized with the developed electro-thermal modeling including transposition effects. After gaining confidence in the developed electro-thermal models, an optimization design toolbox is built for the hybrid-electric engine systems study. The first application study is in partnership with Rolls Royce's Electrically Variable Engine Project to study thermal management system integration effects on motor sizing. The second study is in collaboration with Raytheon Technologies to study motor transient performance with phase change materials integration, which can be tailored to a hybrid-electric engine mission profile

Study on Technology Innovation and Human Resources Reallocation

Economic globalization promotes rapid development of scientific technology. The emergence of technological innovation makes that optimal allocation of human resources has been on the agenda gradually.Relying on technological innovation, enhancing the production efficiency of the enterprises constantly, implementing cost-effective or differentiation are the key of devepment.Human resources in the process of devepment plays an important role in technology innovation.Technology innovation guides the enterprises to implement human resources reallocation for reducing the cost of human resources and strengthening the flow of human resource and the usage efficiency.Human resources as the most basic element of enterprise, is the subject of technological innovation.From the points of technical innovation and human resources,this paper analyzes the relationship between them,reveals the principle of the interaction effects, discusses the strategy of human resource reallocation under the technological innovation

Clinical effect of neovascular glaucoma treated by vitrectomy and cyclophotocoagulation

AIM: To observe the postoperative intraocular pressure(IOP)and operation safety in the eyes of the neovascular glaucoma pateints treated by intraocular cyclophotocoagulation which needed vitrectomy at the same time. <p>METHODS: A total of 12 neovascular glaucoma cases(14 eyes)secondary to diabetic retinopathy, retinal detachment surgery and trauma were reviewed in our study. This procedure mainly used intraocular photocoagulation catheter to highlight the ciliary processes until the ciliary became white atrophy or plosion after vitreous surgery treatment. The intraocular photocoagulation catheter was performed at a power of 300-500mW, for a duration of 0.1-0.2ms. Postoperative follow-up was at least for 6mo. The observation of 14 postoperative neovascular glaucoma was performed at 1wk, 1, 6mo observing the IOP and complications. <p>RESULTS: IOP of the 11 eyes was significantly declined and controlled in normal. After cyclophotocoagulation, average IOP at 1wk was 16.7±14.4mmHg, 15.7±8.8mmHg at 1mo and 12.9±4.5mmHg at 6mo, which compared with untreatment(39.6 ±10.0mmHg)was statistically significant different(<i>P</i><0.01). In follow up time 3 cases were relapsed which were supplied with transscleral or endoscope cyclophotocoagulation. During the follow-up period no endophthalmitis and complications such as eyeball atrophy were found. <p>CONCLUSION: The intraocular cyclophotocoagulation and vitrectomy simultaneously can deal with the primary disease and secondary neovascular glaucoma. The operation can be accurately performed under direct cyclophotocoagulation and it is a safe and effective way for neovascular glaucoma which needs vitreous surgery

Optical Non-Reciprocity in Coupled Resonators Inspired by Photosynthetic Energy Transfer

Inspired by the photosynthetic energy transfer process, we theoretically propose a method to realize non-reciprocal optical transmission in an array of coupled resonators. The optical non-reciprocity of the coupled resonators arises from the frequency gradient between adjacent cavities and the interaction with the environment, which is similar to photosynthetic energy transfer. An increase in the frequency gradient or the number of the cavities can lead to better non-reciprocity. However, although a higher environment temperature will increase the total photon number in the coupled cavities, non-reciprocity will be weakened. All these findings can be well described by the detailed balance. Our discovery reveals the similarity between the noise-induced optical non-reciprocity and exciton energy transfer in natural photosynthesis.Comment: 6 pages, 8 figure