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Search Results: 1 - 10 of 4944 matches for " Christoph Kleinn "
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Enhanced Structural Complexity Index: An Improved Index for Describing Forest Structural Complexity  [PDF]
Philip Becksch?fer, Philip Mundhenk, Christoph Kleinn, Yinqiu Ji, Douglas W. Yu, Rhett D. Harrison
Open Journal of Forestry (OJF) , 2013, DOI: 10.4236/ojf.2013.31005
Abstract:

The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural

On the exposure of hemispherical photographs in forests
Becksch?fer P,Seidel D,Kleinn C,Xu J
iForest : Biogeosciences and Forestry , 2013, DOI: 10.3832/ifor0957-006
Abstract: At least 10 different methods to determine exposure for hemispherical photographs were used by scientists in the last two decades, severely hampering comparability among studies. Here, an overview of the applied methods is reported. For the standardization of photographic exposure, a time-consuming reference measurement in the open land towards the unobstructed sky was required so far. The two Histogram Methods proposed here make use of the technical advances of digital cameras which enable users to assess a photograph’s histogram directly at the location of measurement. This avoids errors occurring due to variations in sky lighting happening in the time span between taking the reference measurement and reaching the sample location within the forest. The Histogram Methods speed up and simplify taking hemispherical photographs, and introduce an objectively applicable, standardized approach. We highlight the importance of correct exposure by quantifying the overestimation of gap fraction resulting from auto-exposed photographs under a wide range of canopy openness situations. In our study, gap fraction derived from auto-exposed photographs reached values up to 900% higher than those derived from non-overexposed photographs. By investigating the size of the largest gap per photograph and the number of small gaps (gaps contributing less than 0.1% to gap fraction), we concluded that the overestimation of gap fraction resulted mainly from the overexposure of vegetation surrounding large gaps.
Establishing Payment Hubs—Unwind the Spaghetti?  [PDF]
Christoph Markert
American Journal of Industrial and Business Management (AJIBM) , 2014, DOI: 10.4236/ajibm.2014.44024
Abstract:

Banks and financial services providers are facing a more and more competitive business within the retail banking as well as corporate market. Increasing productivity and efficiency by decreasing operational costs is very often one milestone on the strategic business roadmap of a bank or financial services providers. The payment area is usually seen as a cost intensive, but necessary part of the business and information technology (IT) landscape. Many banks and financial services providers do still follow a best-of-breed approach within the system payments landscape, which ends up in high operational and maintenance costs as different payment processing platforms are serving different business purposes. The establishment of a single globally centralized payment hub cannot be only the solution for the ending of a heterogeneous payment processing landscape, but also for supporting the strategic management roadmap by decreasing system complexity and increasing the efficiency of the payment platforms and thus decreasing operational and maintenance IT costs. Furthermore it can support banks to establish a far more flexible technological implementation approach for an entire core banking transformation program. This paper is analyzing the challenges and issues banks and financial services providers are facing with the establishment of payment hubs in their enterprise system landscape from a management as well as IT point of view.

Determination of Material Properties like Permittivity and Density with Microwaves  [PDF]
Christoph Sklarczyk
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.56043
Abstract:

With the help of electromagnetic waves in deci-, centi- and millimeter-wave range (microwaves) it is possible to determine the properties of non-metallic objects like permittivity or density in a nondestructive and if necessary in a contactless way. Depending on the type of the test object the measurement can be carried out both with low-cost narrowband or more expensive wideband devices and sensors. To get the characteristic value in most cases it is necessary to calibrate the test device with the help of reference materials. It is recommendable to sustain a constant distance (lift-off or standoff) between the antenna of the sensor and the test object. The paper deals with the characterization of asphalt, especially the determination of its density.

Photon Structure Function Revisited  [PDF]
Christoph Berger
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.68107
Abstract: The flux of papers from electron positron colliders containing data on the photon structure function \"\"ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with \"\", both characteristics being dramatically different from hadronic structure functions. The agreement of the experimental observations with the theoretical calculations is a striking success of QCD. It also allows a new determination of the QCD coupling constant \"\"which very well corresponds to the values quoted in the literature.
Optimal Costly Information Gathering in Public Service Provision  [PDF]
Paul Geertsema, Christoph Schumacher
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.23060
Abstract: Imperfect information regarding the true needs of recipients is a common problem for governmental or not-for-profit service providers. This can lead to potentially dangerous under-provision or wasteful over-provision of services. We provide a method for optimally improving a service provider’s information regarding true client need through costly information gathering. Our contribution is to allow providers to endogenously and optimally choose the intensity of information gathering. Providers do so by specifying the level of correlation between observed and true recipient need, subject to an arbitrary cost function over the specified correlation. We derive the conditions that characterize the choice of optimal correlation for providers with quadratic utility. Using a realistic exponential correlation cost function, we show that there exists a critical value of true client need variance below which it is never optimal to engage in information gathering. Further, for true client variance above this critical level the optimal correlation will always exceed 0.5. Our findings have a wide range of policy implications in areas such as health care, social wellfare and even counter-terroism.
Relative importance of different physical processes on upper crustal specific heat flow in the Eifel-Maas region, Central Europe and ramifications for the production of geothermal energy  [PDF]
Lydia Dijkshoorn, Christoph Clauser
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.52A039
Abstract:

We study the recent upper crustal heat flow variations caused by long-term physical processes such as paleoclimate, erosion, sedimentation and mantle plume upwelling. As specific heat flow is a common lower boundary condition in many models of heat en fluid flow in the Earth’s crust we quantify its long-term transient variation caused by paleoclimate, erosion or sedimentation, mantle plume upwelling and deep groundwater flow. The studied area extends between the Eifel mountains and the Maas river inCentral Europe. The total variation due to these processes in our study area amounts to tectonic events manifested in the studied area 20 mW/m2, about 30% of the present day specific heat flow in the region.

A Methodology to Assess the Safety of Aircraft Operations When Aerodrome Obstacle Standards Cannot Be Met  [PDF]
Hartmut Fricke, Christoph Thiel
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.52007
Abstract: When Aerodrome Obstacle Standards cannot be met as a result of urban or technical development, an aeronautical study can be carried out with the permission of EASA, in conjunction with ICAO, to prove how aircrafts can achieve an equivalent level of safety. However currently, no detailed guidance for this procedure exists. This paper proposes such a safety assessment methodology in order to value obstacle clearance violations around airports. This method has already been applied to a safety case at Frankfurt Airport where a tower elevating 4 km out of threshold 25R severely violates obstacle limitation surfaces. The model data refers to a take-off and landing performance model (TLPM) computing precisely aircraft trajectories for both standard and engine out conditions at ground proximity. The generated tracks are used to estimate collision risk incrementally considering EASA/FAA, EU-OPS & ICAO clearance criteria. Normal operations are assessed with a probabilistic analysis of empirical take-off/landing track data generating the local actual navigation performance (ANP) on site. The ANP shows integration to collision risk for an aircraft with any obstacle. The obstacle is tested for clearance within a “5-step-plan” against all performance requirements for landing climb and take-off climb. The methodology thereby delivers a comprehensive risk picture: The presented safety case for Frankfurt Airport showed an equivalent safety level despite the violation of standards. The collision risk during both normal and degraded performance operations was still found to be within ICAO Collision Risk Model (CRM) limits, requiring only limited risk mitigation measures. The presented work should complement ICAO Doc 9774 Appendix 3.
The Planck Length and the Constancy of the Speed of Light in Five Dimensional Spacetime Parametrized with Two Time Coordinates  [PDF]
Christoph K?hn
Journal of High Energy Physics, Gravitation and Cosmology (JHEPGC) , 2017, DOI: 10.4236/jhepgc.2017.34048
Abstract: In relativity and quantum field theory, the vacuum speed of light is assumed to be constant; the range of validity of general relativity is determined by the Planck length. However, there has been no convincing theory explaining the constancy of the light speed. In this paper, we assume a five dimensional spacetime with three spatial dimensions and two local time coordinates giving us a hint about the constancy of the speed of light. By decomposing the five dimensional spacetime vector into four-dimensional vectors for each time dimension and by minimizing the resulting action, for a certain class of additional time dimensions, we observe the existence of a minimal length scale, which we identify as the Planck scale. We derive an expression for the speed of light as a function of space and time and observe the constancy of the vacuum speed of light in the observable universe.
ara Mo ilor – a Regional Term between Economic and Ecological Interests. Some Explorations in the Romanian Periphery
CHRISTOPH WAACK,CHRISTOPH WAACK
Romanian Review of Regional Studies , 2005,
Abstract: The term “ ara Mo ilor” is very frequently used in the context of the planned gold mining project in Ro ia Montan . The term is as well used in an economic and ecologic way and it is used by those who support the project as well as by its critics. There are a lot of articles in Romanian newspapers and brochures of the last three years combining the gold mining project and the ara Mo ilor topic. It will be analyzed in what different contexts the geographical term is used and the spatial image of ara Mo ilor that is produced in the respective context. Starting with a look into the history of instrumentality of the region it is obvious that there exists a long tradition in using this term for a strong mentality of people who defend their freedom. In an actual context the every day communication of the local population is reproducing this stereotype. The results of a questionnaire shows that the stereotypes used by developer and opponents of the gold mining project met with a strong response. By this way the production and reproduction of a spatial image called “ ara Mo ilor“ can be used successfully for the interests of the actors of both sides. But there exists a geographical differentiation on a small scale between mining and silvicultural areas. This paper focuses on the term “ ara Mo ilor” which is very frequently used when reference is made to the planned gold mining project in Ro ia Montan . The term is also used in economic and ecologic studies and it is used by those who support the project as well as by its critics. There are many articles in Romanian newspapers and brochures of the last three years, which tackle both the gold mining project and the ara Mo ilor topic. Journalists and the public seem to be interested in this matter. I have relied on those arguments which are against the project, as pointed out in Formula AS and on a brochure published in 2002 with the sponsorship of the gold mining company involved in the project. We shall analyze the different contexts where the geographical term is used and the spatial image of ara Mo ilor produced in the respective context.
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