Approaches to integrated strategic/tactical forest planning

Traditionally forest planning is divided into a hierarchy of planning phases. Strategic planning is conducted to make decisions about sustainable harvest levels while taking into account legislation and policy issues. Within the frame of the strategic plan, the purpose of tactical planning is to schedule harvest operations to specific areas in the immediate few years and on a finer time scale than in the strategic plan. The operative phase focuses on scheduling harvest crews on a monthly or weekly basis, truck scheduling and choosing bucking instructions. Decisions at each level are to a varying degree supported by computerized tools. A problem that may arise when planning is divided into levels and that is noted in the literature focusing on decision support tools is that solutions at one level may be inconsistent with the results of another level. When moving from the strategic plan to the tactical plan, three sources of inconsistencies are often present; spatial discrepancies, temporal discrepancies and discrepancies due to different levels of constraint. The models used in the papers presented in this thesis approaches two of these discrepancies. To address the spatial discrepancies, the same spatial resolution has been used at both levels, i.e., stands. Temporal discrepancies are addressed by modelling the tactical and strategic issues simultaneously. Integrated approaches can yield large models. One way of circumventing this is to aggregate time and/or space. The first paper addresses the consequences of temporal aggregation in the strategic part of a mixed integer programming integrated strategic/tactical model. For reference, linear programming based strategic models are also used. The results of the first paper provide information on what temporal resolutions could be used and indicate that outputs from strategic and integrated plans are not particularly affected by the number of equal length strategic periods when more than five periods, i.e. about 20 year period length, are used. The approach used in the first paper could produce models that are very large, and the second paper provides a two-stage procedure that can reduce the number of variables and preserve the allocation of stands to the first 10 years provided by a linear programming based strategic plan, while concentrating tactical harvest activities using a penalty concept in a mixed integer programming formulation. Results show that it is possible to use the approach to concentrate harvest activities at the tactical level in a full scale forest management scenario. In the case study, the effects of concentration on strategic outputs were small, and the number of harvest tracts declined towards a minimum level. Furthermore, the discrepancies between the two planning levels were small

On the Property Rights System of the State Enterprises in China

Detailed analysis of spinal deformity is important within orthopaedic healthcare, in particular for assessment of idiopathic scoliosis. This paper addresses this challenge by proposing an image analysis method, capable of providing a full three-dimensional spine characterization. The proposed method is based on the registration of a highly detailed spine model to image data from computed tomography. The registration process provides an accurate segmentation of each individual vertebra and the ability to derive various measures describing the spinal deformity. The derived measures are estimated from landmarks attached to the spine model and transferred to the patient data according to the registration result. Evaluation of the method provides an average point-to-surface error of 0.9 mm ± 0.9 (comparing segmentations), and an average target registration error of 2.3 mm ± 1.7 (comparing landmarks). Comparing automatic and manual measurements of axial vertebral rotation provides a mean absolute difference of 2.5° ± 1.8, which is on a par with other computerized methods for assessing axial vertebral rotation. A significant advantage of our method, compared to other computerized methods for rotational measurements, is that it does not rely on vertebral symmetry for computing the rotational measures. The proposed method is fully automatic and computationally efficient, only requiring three to four minutes to process an entire image volume covering vertebrae L5 to T1. Given the use of landmarks, the method can be readily adapted to estimate other measures describing a spinal deformity by changing the set of employed landmarks. In addition, the method has the potential to be utilized for accurate segmentations of the vertebrae in routine computed tomography examinations, given the relatively low point-to-surface error

Optimal Trade-Off Between Economic Activity and Health During an Epidemic

This paper considers a simple model where a social planner can influence the spread-intensity of an infection wave, and, consequently, also the economic activity and population health, through a single parameter. Population health is assumed to only be negatively affected when the number of simultaneously infected exceeds health care capacity. The main finding is that if (i) the planner attaches a positive weight on economic activity and (ii) it is more harmful for the economy to be locked down for longer than shorter time periods, then the optimal policy is to (weakly) exceed health care capacity at some time.Comment: 12 pages, 2 figure

On the geometry and topology of initial data sets with horizons

We study the relationship between initial data sets with horizons and the existence of metrics of positive scalar curvature. We define a Cauchy Domain of Outer Communications (CDOC) to be an asymptotically flat initial set $(M, g, K)$ such that the boundary $\partial M$ of $M$ is a collection of Marginally Outer (or Inner) Trapped Surfaces (MOTSs and/or MITSs) and such that $M\setminus \partial M$ contains no MOTSs or MITSs. This definition is meant to capture, on the level of the initial data sets, the well known notion of the domain of outer communications (DOC) as the region of spacetime outside of all the black holes (and white holes). Our main theorem establishes that in dimensions $3\leq n \leq 7$, a CDOC which satisfies the dominant energy condition and has a strictly stable boundary has a positive scalar curvature metric which smoothly compactifies the asymptotically flat end and is a Riemannian product metric near the boundary where the cross sectional metric is conformal to a small perturbation of the initial metric on the boundary $\partial M$ induced by $g$. This result may be viewed as a generalization of Galloway and Schoen's higher dimensional black hole topology theorem \cite{GS06} to the exterior of the horizon. We also show how this result leads to a number of topological restrictions on the CDOC, which allows one to also view this as an extension of the initial data topological censorship theorem, established in \cite{EGP13} in dimension $n=3$, to higher dimensions.Comment: Final version. To appear in Asian Journal of Mathematic

HIROIMONO is NP-complete

In a Hiroimono puzzle, one must collect a set of stones from a square grid, moving along grid lines, picking up stones as one encounters them, and changing direction only when one picks up a stone. We show that deciding the solvability of such puzzles is NP-complete

WHY BUSINESS PLANS AND PLANNING?

The writing of a business plan has become increasingly more highlighted in the academic world during the last few years as courses are being taught on the subject and a number of competitions have been started. Lund Institute of Technology co-organises an annual business plan competition called Venture Cup in order to encourage students and other participants to get into entrepreneurship. People arguing in favour of writing a business plan often mention the possibility to test the idea theoretically before going live as a big advantage. The business plan offers a framework to perform the necessary studies in order to find out if the idea has the potential of becoming a success. A common argument against writing a business plan is that if the entrepreneurs are not looking to attract any funding, they find the writing process to be a waste of time as they will not show the plan to any outsiders. The author’s interest in writing business plans arose during a course at Lund Institute of Technology called Entrepreneurship and Business Development. He found it very interesting to combine the engineering aspects of his education with the business skills required for the planning of a business. The author wanted to learn more about the process of developing an idea and turning it into a successful business and it is his belief that a business plan is the best tool for success in this case. The business idea described in this thesis is a juicebar. Once the business idea had been chosen, the author started to conduct background research. The primary data is mainly based on interviews with advisors at banks,governmental support organisations, unions, commercial consultants and sales representatives of various suppliers. Information has also been gathered from a market survey conducted among potential customers. The juicebar described is intended to offer its customers fresh fruit drinks, served in an environment which gives an healthy impression. The bar should be an alternative to smoky cafés and stressful snack-bars. The bar should be opened in the centre of Leuven, Belgium, where it is close to shoppers, students and tourists who pass by on a daily basis. The products are primarily aimed at young working people and students who are interested in living a healthy life. The market analysis and other research show that there are certain risks with this business idea. The main risk lies within attracting customers. Further market survey will be required before the plans can become reality, but the author is sure of the idea’s opportunities. It is the intention of the author to prepare against these risks by gathering information and advice from more experienced entrepreneurs, who he will meet through a sponsor programme. The lessons learned from writing the business plan are that planning the business is essential and that the writing of the business plan itself will force the entrepreneur to think about things that he otherwise would not have thought about on beforehand. A well-written business plan can turn into a very detailed blueprint for how to construct the business and it will be a roadmap to follow when the business is up and running

Investigating the generality of time-local master equations

Time-local master equations are more generally applicable than is often recognised, but at first sight it would seem that they can only safely be used in time intervals where the time evolution is invertible. Using the Jaynes-Cummings model, we here construct an explicit example where two different Hamiltonians, corresponding to two different non-invertible and non-Markovian time evolutions, will lead to arbitrarily similar time-local master equations. This illustrates how the time-local master equation on its own in this case does not uniquely determine the time evolution. The example is nevertheless artificial in the sense that a rapid change in (at least) one of the Hamiltonians is needed. The change must also occur at a very specific instance in time. If a Hamiltonian is known not to have such very specific behaviour, but is "physically well-behaved", then one may conjecture that a time-local master equation also determines the time evolution when it is not invertible.Comment: 7 pages, 6 figure

Validating the Harmonic Balance Method for Turbomachinery Tonal Noise Predictions

A computational method for predicting turbomachinery tonal noise is presented. It is based on the Harmonic Balance method, which solves for the dominant frequencies of the flow generated by bladerow interaction. Coupling between the resolved frequencies is furthermore enabled since the Harmonic Balance method is applicable to the nonlinear Euler or Navier-Stokes equations. The implementation is also validated against two cases from the Fourth Computational Aeroacoustics Workshop on Benchmark Problems hosted by NASA. The computational setup is explained in detail and specific challenges encountered in both benchmark problems are discussed. Results generally show very good agreement with data published by several other authors, giving confidence in the capability of the method. Some remaining challenges for the implemented method necessary to compute full scale turbomachinery noise are also identified and discussed