The eleven antenna: a compact low-profile decade bandwidth dual polarized feed for reflector antennas

A novel dual polarized ultrawide-band (UWB) feed with a decade bandwidth is presented for use in both single and dual reflector antennas. The feed has nearly constant beam width and 11 dBi directivity over at least a decade bandwidth. The feed gives an aperture efficiency of the reflector of 66% or better over a decade bandwidth when the subtended angle toward the sub or main reflector is about 53°, and an overall efficiency better than 47% including mismatch. The return loss is better than 5 dB over a decade bandwidth. The calculated results have been verified with measurements on a linearly polarized lab model. The feed has no balun as it is intended to be integrated with an active 180° balun and receiver. The feed is referred to as the Eleven antenna because its basic configuration is two parallel dipoles 0.5 wavelengths apart and because it can be used over more than a decade bandwidth with 11 dBi directivity. We also believe that 11 dB return loss is achievable in the near future

Enabling Economic Growth

In this thesis I argue that the absence of energy utilization as a component in contemporary economic history and economic growth theory severely limits our understanding of economic development as a process. Although energy is not sufficient to explain the unprecedented expansion in the world economy since the industrial revolution, it is however absolutely necessary. Technological progress remains the direct cause of economic growth in the long run, but innovativeness must be facilitated by economically beneficial institutions. There is a broad consensus about institutions as the engine behind long term growth. My intention is not to challenge that notion, but I want to stress that pinpointing those exact benign institutions has proven to be very difficult. And even when we accept institutions as central to economic growth, one question remains: What has caused the differences in institutional outcomes across the globe? It has been widely suggested that competition is the key to institutional development, but I will argue that a purely quantitative outlook on competition does not explain institutional outcomes. Instead I suggest a more qualitative approach in the concept of contextual dynamism

Call Options and Accruals Quality

We analyze the link between financial reporting choices that affect accruals quality and firms' use of call options. We argue that call options used in compensation arrangements (employee stock options or ESOs) create countervailing incentives for managers to affect accruals quality. On the one hand, poorer accruals quality is associated with greater returns volatility (which leads to an increase in ESO value); on the other hand, better accruals quality is associated with a lower cost of capital (and, therefore, higher share price, which leads to an increase in ESO value). We confirm both effects on accruals quality, and we show that the net effect is for ESOs to worsen accruals quality. We provide additional evidence on this main result by showing that in two settings where the returns volatility incentive to worsen accruals quality is muted or absent (cases where managers hold employer shares and cases where the firm uses call options for financing purposes, such as preferred stock and convertible debt), the overall incentive is for managers to increase accruals quality.Options; Information Quality; Compensation

Applications using estimates of forest parameters derived from satellite and forest inventory data

From the combination of optical satellite data, digital map data, and forest inventory plot data, continuous estimates have been made for several forest parameters (wood volume, age and biomass). Five different project areas within Sweden are presented which have utilized these estimates for a range of applications. The method for estimating the forest parameters was a ”k-Nearest Neighbor” algorithm, which used a weighted mean value of k spectrally similar reference plots. Reference data were obtained from the Swedish National Forest Inventory. The output was continuous estimates at the pixel level for each of the variables estimated. Validation results show that accuracy of the estimates for all parameters was low at the pixel level (e.g., for total wood volume RMSE ranged from 58-80%), with a tendency toward the mean, and an underestimation of higher values while overestimating lower values. However, when the accuracy of the estimates is assessed over larger areas, the errors are lower, with best results being 10% RMSE over a 100 ha aggregation, and 17% RMSE over a 19 ha aggregation. Applications presented in this paper include moose and bird habitat studies, county level planning activities, use as input information to prognostic programs, and computation of statistics on timber volume within drainage basins and smaller land holdings. This paper provides a background on the kNN method and gives examples of how end users are currently applying satellite-produced estimation data such as these

The Market Pricing of Accruals Quality

We investigate whether investors price accruals quality, our proxy for the information risk associated with earnings. Measuring accruals quality (AQ) as the standard deviation of residuals from regressions relating current accruals to cash flows, we find that poorer AQ is associated with larger costs of debt and equity. This result is consistent across several alternative specifications of the AQ metric. We also distinguish between accruals quality driven by economic fundamentals ('innate AQ') versus management choices ('discretionary AQ'). Both components have significant cost of capital effects, but innate AQ effects are significantly larger than discretionary AQ effects.Expected return; Information uncertainty; Accounting quality

Integrative taxonomy of the Plain‑backed Thrush (Zoothera mollissima) complex (Aves, Turdidae) reveals cryptic species, including a new species

Background: The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China.It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to be broadlysympatric. Methods: We revise the Z. mollissima-Z. dixoni complex by integrating morphological, acoustic, genetic (two mitochondrialand two nuclear markers), ecological and distributional datasets. Results: In earlier field observations, we noted two very different song types of "Plain-backed" Thrush segregated by breeding habitat and elevation. Further integrative analyses congruently identify three groups: an alpine breeder inthe Himalayas and Sichuan, China ("Alpine Thrush"); a forest breeder in the eastern Himalayas and northwest Yunnan(at least), China ("Himalayan Forest Thrush"); and a forest breeder in central Sichuan ("Sichuan Forest Thrush"). Alpine and Himalayan Forest Thrushes are broadly sympatric, but segregated by habitat and altitude, and the same is probablytrue also for Alpine and Sichuan Forest Thrushes. These three groups differ markedly in morphology and songs.In addition, DNA sequence data from three non-breeding specimens from Yunnan indicate that yet another lineage exists ("Yunnan Thrush"). However, we find no consistent morphological differences from Alpine Thrush, and its breedingrange is unknown. Molecular phylogenetic analyses suggest that all four groups diverged at least a few million years ago, and identify Alpine Thrush and the putative "Yunnan Thrush" as sisters, and the two forest taxa as sisters. Cytochrome b divergences among the four Z. mollissima sensu lato (s.l.) clades are similar to those between any ofthem and Z. dixoni, and exceed that between the two congeneric outgroup species. We lectotypify the name Oreocincla rostrata Hodgson, 1845 with the Z. mollissima sensu stricto (s.s.) specimen long considered its type. No availablename unambiguously pertains to the Himalayan Forest Thrush. Conclusions: The Plain-backed Thrush Z. mollissima s.l. comprises at least three species: Alpine Thrush Z. mollissima s.s., with a widespread alpine breeding distribution; Sichuan Forest Thrush Z. griseiceps, breeding in central Sichuan forests; and Himalayan Forest Thrush, breeding in the eastern Himalayas and northwest Yunnan (at least), which is described herein as a new species. "Yunnan Thrush" requires further study

V-GQM: a feed-back approach to validation of a GQM study

The Goal/Question/Metric paradigm is used for empirical studies on software projects. Support is given on how to define and execute a study. However, the support for running several subsequent studies is poor. V-GQM introduces a life-cycle perspective, creating a process, spanning several GQM studies. After the GQM study has been completed, an analysis step of the plan is initiated. The metrics are analysed to investigate if they comply with the plan or has extended it, and also to investigate if the metrics collected answer more questions than posed in the plan. The questions derived from metrics are then used to form the goal for the next GQM study, effectively introducing a feed-back loop. By introducing the bottom-up approach, a structured analysis of the GQM study is possible when constructing several consecutive GQM studies. A case study, using V-GQM, is performed in an industrial setting

Ring test for evaluation of bond properties of reinforcing bars

ABSTRACT A pull-out bond test with short bond length for estimation of the splitting tendency of different rib shapes for reinforcing bars is proposed and investigated. In the test the bond force component along the bar is separated from the radial one. The radial component is determined by measuring circumferential strain in a steel ring surrounding the concrete of the pull-out specimen. The force component, which is longitudinal to the bar, is obtained by supporting the pull-out specimen with a teflon covered circular support close to the bar. Bars with specially turned ribs are studied concerning rib height and rib distance. Swedish standard high bond bars are also studied. The splitting tendency is stated as a function of the slip of the free bar end and also of the related rib area of the bars

Study of springback of green bodies using micromechanical experiments and the discrete element method

The Discrete Element Method (DEM) is today a commonly used tool to simulate compaction of particulate media. The main issue when using DEM in compaction problems is the description of the contact between two powder particles. If the material properties are known, analytical and semi-analytical methods can be used [1,2] but for many industrial applications, for instance spray dried granules, the mechanical behaviour is unknown. The compaction behaviour and green properties of a cemented carbide powder is studied in this work and the issue of the contact description is solved by performing experiments on the powder granules. Firstly, compression tests are made on the single granules giving information of the mechanical properties at low strains. To get information at high strains, which are needed in powder compaction simulations, nanoindentation tests are performed. The measured material parameters are used in a FE model of two spheres in contact and the resulting contact law is exported to a DEM program. The DEM program is used to investigate the compaction properties of a powder compact and especially the springback during unloading which is important for predicting the final shape of the product. The results are compared with presently performed experiments and the applicability range of the discrete element simulations will be discussed