基于载流子平衡的效率及亮度提高的有机蓝光器件

研究了在两空穴传输层之间插入Bphen中间层对有机蓝光器件(BOLEDs)效率的影响。结果表明,其对空穴的阻挡作用使得电子与空穴在发光区内达到相对平衡,减少了激子-极化子猝灭几率,从而提高了有机蓝光器件的效率和亮度。器件的最大电流效率从16.12 cd/A增加到20.52 cd/A,相对提高了27.30%;最大功率效率从14.23 lm/W增加到17.64 lm/W,相对提高了23.96%。文中对提高效率的物理机制进行了详细的阐述。

Analysis of Land Use Change and Driving Force of Bole City Based on Remote Sensing Image

[Objectives] The land use change and its influence has been the frontier and hotspot in the research of the surface process of change. The aim of this study was to provide a reasonable scientific basis for the more reasonable use of regional land resources of Bole City by study of land use change and driving force of Bole City.[Methods] Through geometric correction, image mosaic and image registration processing and classification of the remote sensing images of Bole City in 2006, 2011 and 2016, the three images of land use change in land use types （land use change range, dynamic degree and variation degree） were studied, and the natural and social economy in terms of the driving forces of land use change were analyzed.[Results] In the 2006 to 2016 period, cultivated land of Bole City had the land use dynamic growth state, and the average growth rate was 0.26%; and forest land, construction land, water, grassland and unused land showed a decreasing trend, decreased by 0.23%, 0.22%, 0.75%, 3.85% and 1.52%, respectively. In the entire study period, the change of grassland was the biggest, the changes of unused land and water were the second, and the changes of cultivated land, construction land and forest land were lesser.[Conclusions] The main driving factors that effected on land use change of the study area were climate, industrialization, urbanization, social and economic activities, adjustment of agricultural structure and population expansion.

Distributed In-Time Multiple Coverage Holes Healing Protocol

Coverage holes often appear in wireless sensor networks due to sensor failure or the inheritance of sensor＇s random distribution. In the hybrid model, mobile sensors in the network are acquired to heal coverage holes by their mobifity. When multiple coverage holes appear in the sensor network and each of them has a time requirement （in which the coverage hole has to be healed）, conflicts for the requests of the same mobile sensor may arise. A distributed multiple mobile sensor schedufing protocol （DMS） is proposed in this paper to solve this problem by finding mobile sensors in the time response zone defined by the time requirement of each coverage hole. Simulation results show that DMS can well schedule the mobile sensors to move to multiple coverage holes within the time requirement.

Do Epiphytes in Drier Climates Select Host Tree Substrates between Rough and Smooth Bole Textures and Crown and Stem, Vertical and Upright Stems? What Are the Implications for Water Catchment and Forest Management?

Epiphyte biomass (dry weight kg) placement between rough and smooth bole bark textures;crown and trunk as well as upright and horizontal substrates in Lusenga National Park were examined through ground surveys. Transects were located at random in woody vegetation using quadrats 20 m × 20 m which were located every 100 m along 1 km long transects. For every host tree substrate sampled, tree species was identified and bark texture was determined. Presence and location of epiphytes were determined through direct observation. Epiphytes were collected, dried and weighed, so as to apportion biomass between rough and smooth bole textures, crown and trunk as well as stem inclination. Rough bole textured stems had more epiphytes of 1967 kg (89%) than smooth bole substrates of 313.48 kg (11%) and also inclined stems had higher biomass of 85% than vertical stems of 14.64% (χ2 = P < 0.005). Trunk had less biomass of 32% and crown had higher biomass of 68% (Mann Whitney U test 0.002 < P < 0.05). It was concluded that epiphytes were more abundant on rough bole textured substrates and in crown than stem. It would appear that rough bole textured substrates provided better physical anchorage and stability against dislodging forces of wind and rain water, hence being suitable for epiphyte establishment and survival. Inclined substrates on the other hand provided a suitable habitat for accumulation of debris and moisture retention, seed settling, germination, and maximum exposure to sunlight all of which support germination and growth of epiphytes. Further research is required to determine successional colonization, incidences of host species specificity, rain water interception and retention and impact of fire on epiphyte biomass as these are important water catchment attributes.

Canonical Shape Analysis of Hausa and Bole Ideophones

Hausa and Bole are two languages from the same phylum i.e. Afro-asiatic. They have some common various linguistic features, most especially phonological and syntactic features. The main purpose of this paper is to come up with one of the phonological aspects of one of the word classes of Hausa and Bole. This means, we will analyse the syllable structure, which is canonical shape of ideophones of both languages using descriptive method of analysis adopted by Newman (2000). In Hausa, likewise in Bole, ideophones are numerous and several of them are commonly used syntactically. But, we will not deal with their syntactical use or function in this paper, what we focus on, is just their canonical shapes i.e. syllable structures. The paper is divided into four sections: sections one and four are introduction and conclusion respectively, while section two is descriptive analysis of canonical shape of Hausa ideophones, and section three, is of Bole ideophones.

Comparative Assessment of the Relationship of Satellite Data with the Above Ground Biomass of Sal Trees(Shorea robusta) Determined from Phenologically Different Time Periods

The Above Ground Biomass(AGB) estimates of vegetation comprise both the bole biomass determined through a volumetric equation and litter biomass collected from the ground.For mature trees,the AGB estimated in phenologically different time periods is directly affected by the litter biomass since the Diameter at Breast Height(DBH) and height(H) of such trees that are used in the estimation of bole biomass would remain unchanged over a reasonable time period.In the present study,we have determined the AGB of Sal trees(Shorea robusta) in two contrasting seasons:the peak green period in October being devoid of lit-ter on the ground and the leaf shedding period in February with abundant amount of litter present on the ground.Estimation of AGB for the month of February included the litter biomass.In contrast,the AGB for October represented only the bole biomass.AGB was estimated for ten different plots selected in the study area.The AGB estimated from ten sampling plots for each time period was re-gressed with the individual tree parameters such as the average DBH and height of trees measured from the corresponding plots.The regression analysis exhibited a significantly stronger relationship between the AGB and DBH for the month of October as compared to February.Furthermore,the correlation between the remotely sensed derived data and AGB was also found to be significantly higher for the month of October than February.This observation indicates that inclusion of the litter biomass in AGB will tend to decrease the re-gression relationship between AGB and DBH and also between the remotely sensed data and AGB.Therefore,these conclusions invite careful consideration while estimating AGB from satellite data in phenologically different time periods.