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Efficient Sampling Methods for Forest Inventories and Growth ProjectionsYang, Sheng-I 24 June 2019 (has links)
For operational forest management, a forest inventory is commonly conducted to determine the timber stocking and the value of standing trees in a stand. With time and costs constraints, appropriate sampling designs and models are required to perform the inventory efficiently, as well as to obtain reliable estimates for the variables needed to make projections. In this dissertation research, a simulation study was conducted to extensively explore four important topics in forest inventories: selection of measurement trees in point samples, projection from plot- and stand-level aggregations, subsampling height for volume estimation, and updating stand projections using periodic inventories. A series of simulated loblolly pine plantations with varying degrees of spatial heterogeneity were generated at different stages in stand development. Repeated sampling was used to examine various sampling schemes and growth projection methods. Highlights for the four topics follow:
1. Stand total volume can be reliably estimated using measurement trees tallied by Big BAF, point-double sampling, or random selection of a specified number of trees. However, number of trees per unit area in small-size classes were overestimated across the three tree-selection methods when sample data were aggregated into diameter classes.
2. Plot-level and stand-level projections produced similar estimates for dominant height, basal area, and stems per unit area. As spatial heterogeneity increased, stand-level projections indicated a significant bias of predicted total volume compared with the plot-level projections.
3. Sampling intensity, stand age and spatial heterogeneity have greater influence on the reliability for total volume estimation compared to subsampling intensity and measurement error for height measurements.
4.The variability of total volume estimates increases with increasing projection length (i.e., longer time intervals between inventory entry points). However, the estimates of stand total volume can be greatly improved by updating the models with information obtained in periodic forest inventories, especially when the original models are not well calibrated.
The results of this study provide useful guidance and insights for forest practitioners to design forest inventories and improve growth projection systems in operational forest management. / Doctor of Philosophy / For operational forest management, a forest inventory is commonly conducted to determine the timber stocking and the value of standing trees in a stand for management decisions, financial planning and fiduciary reporting requirements. With time and costs constraints, appropriate sampling designs and models are required to perform the inventory efficiently, as well as to obtain reliable estimates for the variables needed to make stand projections. Loblolly pine (Pinus taeda L.) is the primary commercial species in the southeastern United States. In this dissertation research, a simulation study was conducted to extensively explore several important topics in forest inventories, including selection of measurement trees in point samples, projection from plot- and stand-level aggregations, subsampling height for volume estimation, and updating stand projections using periodic inventories. A series of simulated loblolly pine plantations with varying degrees of spatial heterogeneity were generated at different stages in stand development. Repeated sampling was used to examine various sampling schemes and growth projection methods. The results of this study provide useful guidance and insights for forest practitioners to design forest inventories and improve growth projection systems in operational forest management.
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Study of Relationships between Apparel Manufacturers' Supply Chain Management, Company Characteristics, and Inventory PerformanceLee, Yuri 05 May 2000 (has links)
The purpose of this study is to examine apparel manufacturers' inventory performance, which is one of the major performance indicators of supply chain management (SCM) with the consideration of company characteristics. The objectives of the study are (a) to identify the level of SCM activities of apparel manufacturers, (b) to examine the differences of apparel manufacturers' characteristics (i.e., product characteristic, production system, fabric suppliers, retail customers) according to the level of SCM activities, and (c) to illustrate how the SCM activities and apparel manufacturers' characteristics relate to the inventory management performance in terms of levels within the type (i.e., raw material, work-in-process, finished goods). Through an intensive literature review six SCM dimensions and 26 SCM activities were identified and four company characteristics selected for the study were found to influence the company performance. Inventory levels within the type were compared as a result of levels of SCM activities and company characteristics. Data were collected via a self-administered mail questionnaire sent to a random proportional stratified sample of 1,195 US apparel manufacturers in SIC 231 to 234. In the data analyses, 93 returned surveys were used with the adjusted response rate of 9.49%.
Cluster analysis was used to identify the SCM activity groups who showed different levels of SCM activities. Factor analysis was used to determine the number of SCM dimensions and SCM activity scales, and to identify the SCM activity level of each cluster. ANOVA, Chi-square, Tukey-test, matched sample t-test, t-test, regression, and correlation were employed to determine the relationships between SCM activity level, company characteristics and inventory levels within the type.
Statistical analyses supported the research hypotheses. Apparel manufacturers' SCM activity level differs and company characteristics are significantly related with the SCM activity level. Company characteristics and SCM activity level are significantly related with the inventory performance. Findings imply that basic goods manufacturers are more likely to see the benefits of SCM activity implementation in inventory performance. Lead-time for fashion goods procurement, production, and delivery takes longer than basic goods and is hard to be shortened. Limitations of the study and suggestions for future study were discussed. / Ph. D.
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Increasing the efficiency of multiple-use inventory proceduresStuck, Roger Dean January 1976 (has links)
Two approaches were used to evaluate multiple-use inventories. The first approach was to analyze inventory data currently being collected. Assuming that all variables being inventoried are necessary in making decisions for multiple-use management, simple correlation, multiple linear regression, and factor analysis techniques were employed. Data from the Jefferson National Forest in Virginia were analyzed but no strong association between variables currently being observed was detected.
The second approach was to define the decisions that are to be made and the variables necessary to make these decisions. Once the variables have been defined, sampling intensity must be determined. The decision-maker was not required to define the sampling intensity based on experience or a rule-of thumb, but rather a cost-loss function for multiple inventories and multiple decisions was minimized. The cost of collecting data will increase as sample size increases, while the expected monetary loss that will occur to the decision-maker from making decisions with inventory data will decrease. Minimizing the cost-loss function determines the sampling intensity that will provide the lowest total (cost plus loss) monetary cost to the decision-maker. Methods were developed to determine necessary information for the cost-loss function, and several methods of minimization were evaluated. / Doctor of Philosophy
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Strategic Planning Models and Approaches to Improve Distribution Planning in the Industrial Gas IndustryFarrokhvar, Leily 04 May 2016 (has links)
The industrial gas industry represents a multi-billion dollar global market and provides essential product to manufacturing and service organizations that drive the global economy. In this dissertation, we focus on improving distribution efficiency in the industrial gas industry by addressing the strategic level problem of bulk tank allocation (BTA) while considering the effects of important operational issues. The BTA problem determines the preferred size of bulk tanks to assign to customer sites to minimize recurring gas distribution costs and initial tank installation costs. The BTA problem has a unique structure which includes a resource allocation problem and an underlying vehicle routing problem with split deliveries.
In this dissertation, we provide an exact solution approach that solves the BTA problem to optimality and recommends tank allocations, provides a set of delivery routes, and determines delivery amounts to customers on each delivery route within reasonable computational time. The exact solution approach is based on a branch-and-price algorithm that solves problem instances with up to 40 customers in reasonable computational time.
Due to the complexity of the problem and the size of industry representative problems, the solution approaches published in the literature rely on heuristics that require a set of potential routes as input. In this research, we investigate and compare three alternative route generation algorithms using data sets from an industry partner. When comparing the routes generation algorithms, a sweep-based heuristic was the preferred heuristic for the data sets evaluated.
The existing BTA solution approaches in the literature also assume a single bulk tank can be allocated at each customer site. While this assumption is valid for some customers due to space limitations, other customer sites may have the capability to accommodate multiple tanks. We propose two alternative mathematical models to explore the possibility and potential benefits of allocating multiple tanks at designated customer site that have the capacity to accommodate more than one tank. In a case study with 20 customers, allowing multiple tank allocation yield 13% reduction in total costs.
In practice, industrial gas customer demands frequently vary by time period. Thus, it is important to allocate tanks to effectively accommodate time varying demand. Therefore, we develop a bulk tank allocation model for time varying demand (BTATVD) which captures changing demands by period for each customer. Adding this time dimension increases complexity. Therefore, we present three decomposition-based solution approaches. In the first two approaches, the problem is decomposed and a restricted master problem is solved. For the third approach, a two phase periodically restricting heuristic approach is developed. We evaluate the solution approaches using data sets provided by an industrial partner and solve the problem instances with up to 200 customers. The results yield approximately 10% in total savings and 20% in distribution cost savings over a 7 year time horizon.
The results of this research provide effective approaches to address a variety of distribution issues faced by the industrial gas industry. The case study results demonstrate the potential improvements for distribution efficiency. / Ph. D.
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Alight, the dead of night: Ascertaining the collection and use of nighttime site inventory in landscape architecture professional practiceFelkins, Jacob Zachary 13 August 2024 (has links) (PDF)
In landscape architecture, site inventory is a common precursor and perpetual informant of site design, toolkit development, and best management practices. Within inventory-specific texts, inventory is primarily geared, collected, and applied toward the daytime, and thusly, one might consider the bulk of inventory to be “daytime inventory” which pays greater heed to a diurnal humanity and lesser heed to the nocturnal world. With a greater attention to nighttime site conditions, we explored “nighttime inventory” through a series of primary considerations - nighttime lighting, light pollution, site ecology, and the night sky – along with several secondary considerations. We then surveyed 811 landscape practitioners from 12 states - receiving 51 responses - and via Likert, open-response, and yes/no inquiries; we assessed whether practitioners acknowledge and/or design per those nighttime considerations in their professional practice. Summarily, we found landscape practitioners paid less heed to nighttime inventory considerations – with some notable exceptions.
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Förekomst av xerostomi hos studenter på Hälsohögskolan i Jönköping : En enkätstudie / Prevalence of xerostomia in students at School of Health Sciences in JönköpingHakkararinen, Caroline, Benjaminsson, Linda January 2015 (has links)
Background: Xerostomia is the subjective feeling of dry mouth and the state is because of its multifactorial character often limited to treating the symptoms that occurs instead of the causal factors. Xerostomia is a state which may affect both the oral and general health and can therefore have a negative impact on the individuals quality of life. Xerostomia was earlier defined as a state that affected old or sick people but investigations have lately showed that xerostomia also is prevalent in young healthy subjects. Aim: The aim of this study was to investigate the prevalence of xerostomia and potential risk factors in students at School of Health Sciences in Jönköping. Methods: Students from four education programs at School of Health Sciences was asked to participate and fill out a questionnaire including background variables, standard questions of dry mouth and Xerostomia Inventory. Result: Xerostomia was found in 20% of the subjects. These had higher scores on Xerostomia Inventory compared to the subjects without xerostomia. The difference was statistically significant (p≤0,05). Conclusion: Xerostomia is a state that is prevalent in young, healthy subjects and though the state is idiopathic further investigation about its prevalence and the causal factors are needed. / Bakgrund: Xerostomi innebär subjektiv muntorrhet och då tillståndet är av multifaktoriell karaktär begränsas behandling ofta till att lindra individens besvär och symtom. Xerostomi är ett tillstånd som påverkar både individens orala och generella hälsa negativt vilket även kan leda till en nedsatt livskvalitet. Xerostomi betraktades tidigare som ett tillstånd som drabbar äldre och sjuka men senare studier har funnit en förekomst även hos unga friska individer. Syfte: Syftet var att kartlägga prevalens samt möjliga orsaksfaktorer till xerostomi hos studenter på Hälsohögskolan i Jönköping. Metod: Individer som studerade fjärde terminen vid fyra av Hälsohögskolans totalt åtta utbildningsprogram tillfrågades om att besvara en enkät som omfattade bakgrundsvariabler, standardfrågor om muntorrhet samt Xerostomia Inventory. Resultat: Studien påvisade en förekomst av xerostomi hos 20 % av studenterna. Individer med xerostomi uppvisade högre poäng på Xerostomia Inventory än individer utan xerostomi Skillnaden var statistiskt signifikant (p≤0,05). Slutsats: Xerostomi är ett tillstånd som förekommer hos unga friska individer och då tillståndet är idiopatiskt är det angeläget att fortsätta utreda dess förekomst samt potentiella orsaksfaktorer.
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Analysis of inventory control system in rural South African small and medium enterprises.Tladi, Lethamaga Richard. January 2015 (has links)
M. Tech. Business Information Systems / Small and Medium Enterprises (SMEs) are playing a pivotal role in shaping an international economic landscape through job creation and acting as a catalyst in encouraging indigenous-traditional business activities, particularly in rural areas. However, SMEs operate their business with a variety of challenges. For example, the inventory control system is operated manually which results in intensive human errors. The argument driving the study was that a wireless web-based inventory control system could lead to sustenance and competitiveness of rural SMEs. The objective of this study was to; analyse how rural SMEs conduct business and to analyse how manual inventory control system are used, explore issues and challenges experienced which may be affecting the process of conducting business, and lastly to determine how wireless inventory control system could be used appropriately to improve rural SMEs.
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An analysis and implementation of a land environment spare parts scaling model for the Canadian ForcesSwitzer, Jeffrey Charles, 1956- January 1988 (has links)
This thesis examines the spare parts mission scaling problem within the land environment of the Canadian Forces. A revision was done to the recently proposed Land Automated Scaling System, thus providing a readily implementable version of this model. This revised model determines the kit of spare parts for a first or second line unit to carry in order to maximize the operational availability of the deployed weapons systems, subject to a volume constraint. Bayesian methods and actual part demand data are used to revise the demand distribution to more accurately reflect the distribution of the number of parts required during a mission, taking into account the environmental conditions and usage mode of the equipment. The model is easy to use, requiring readily available and easily accessible input data. In addition, it can be operated on a Base minicomputer, thus allowing it to be used by the ordinance engineering and supply officers at the unit/formation level to produce and revise their parts scales as their situation requires.
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Inventory manager's workstation for the Aviation Supply OfficeMarentic, George A. 12 1900 (has links)
Approved for public release; distribution is unlimited / Each inventory manager at the Aviation Supply Office Philadelphia, PA is presently
required to manage approximately 700 line items. To allow the inventory manager a
more efficient method of reviewing and using the data and reports from the Uniform
Inventory Control Point (UICP) computer system, a distributed computer system is
necessary. By downloading the the appropriate inventory data from UICP to a local
computer system, a decision support system (DSS) can be be implemented using existing
off the shelf hardware and software. The ability to replace the present copious paper
reports with concise computerized information and import that data into electronic
spreadsheets for further analysis can greatly improve the inventory manager's
effectiveness. To this end, this thesis provides inventory managers at ASO with access
to the following functions:
Interactive access to the main UICP database.
The ability to use UICP data with a decision support system.
A user interface that is easy to understand and learn.
A local data base which supports working group requirements.
Basic office automation.
This thesis will cover the selection of the hardware and software, data identification
and management and DSS development. A prototype system called the IM Workstation
was developed for this thesis and used to produce the thesis document. COBOL and
ALIS ELF macro program listings are provided. / http://archive.org/details/inventorymanager00mare / Lieutenant, United States Navy
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An Empirical Investigation of the Structural Form and Measurement Validity of the Hill InventoryBlake, Faye W. 08 1900 (has links)
This research began with the Hill Inventory. Cognitive style preference variables were classified as one of following four types: Theoretical Codes, Qualitative Codes, Social-Cultural Codes or Reasoning Modalities. A consumer behavior perspective was then used to form an alternative structure for the Hill Inventory variables. The following three constructs were proposed: Evaluation Codes, Perceptual Codes, and Reasoning Modalities.
The purpose of this research was to assess the structural form and measurement validity of the Hill Inventory. Specific steps taken to accomplish this objective included: developing confirmatory factor and structural equation models; using the LISREL software package to analyze the model specifications; and assessing the validity of the questions used to measure the variables.
A descriptive research design was used to compare the model specifications. The research instrument consisted of eight statements for each of twenty-eight variables for a total of 224 questions. Five-point response choices were described by the words: often, sometimes, unsure, rarely, or never. The sample consisted of 285 student subjects in marketing classes at a large university.
Data analysis began by comparing the distributions of the data to a normal case. Parameter estimates, root mean square residuals and squared multiple correlations then were obtained using the LISREL VI software package. The chi-square statistic was used to test the hypotheses. This statistic was supplemented by the Tucker-Lewis index which used a null model for comparisons. The final step in data analysis was to assess the reliability of the measurements.
This study affected the potential usage of the Hill Inventory for consumer behavior research. The major conclusion was that the measurement of the variables must be improved before model parameters can be tested. Specific question sets on the inventory were identified that were most in need of revision.
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