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1.
面向21世纪的中国林业遥感   总被引:12,自引:0,他引:12  
重点概述了近20年来林业遥感专家们为改进森林资源调查方法所作的诸多努力,如用卫星数据估计森林蓄积量、小块林地面积、以及森林郁闭度方法的研究、森林动态图的编制等。特别是上述方法在经过森林调查实际应用并进行效益分析后,提出的改进现行调查体系的建议。此外还提及了遥感用于评估、监测森林生态环境和森林灾害等方面取得的进展。对21世纪中国林业遥感前景进行了展望。作者认为下一个世纪中国林业遥感发展的主要方向是:包容各种新技术,形成新的技术体系,并与国际接轨;利用遥感的优势,研究森林的宏观状况与作用;与森林经营进一步结合。  相似文献   

2.
林业的可持续发展,是以森林资源为基础的,因此必须加强森林资源的培育。提高对森林资源的调查设计,是实现林业可持续发展的基础条件,所以,我国林业部门应该科学有效的建立起森林调查设计和森林可持续经营的措施。  相似文献   

3.
近年来,我国林业生产发展迅速,森林覆盖率、林木蓄积量都有了大幅变化,现有的档案数据已不能准确反映当前我国森林资源现状,因此,开展森林资源调查工作十分必。本文就森林资源调查工作的点进行初步探讨。  相似文献   

4.
我国森林资源总的变化趋势是:森林面积逐年增加,每年以200万hm^2速度递增,林木生长量开始大于消耗量,森林资源的发展在数量上开始走出“低谷”,扭转了长期以来森林资源下降的局面,实现了森林面积和森林蓄积的“双增长”。森林资源是决定林业生存和发展的基础。森林资源的发展对我国的经济起到了至关重要的作用,所以,林区的整地、造林方法就显得尤为重要,本文主要论述了在实际工作中常用的一些造林方法。  相似文献   

5.
我国森林资源总的变化趋势是:森林面积逐年增加,每年以200万hm^2速度递增,林木生长量开始大于消耗量,森林资源的发展在数量上开始走出“低谷”,扭转了长期以来森林资源下降的局面,实现了森林面积和森林蓄积的“双增长”。森林资源是决定林业生存和发展的基础。森林资源的发展对我国的经济起到了至关重要的作用,因此林区的整地、造林方法就显得尤为重要。主要论述了在实际工作中常用的一些整地与造林方法。  相似文献   

6.
我国森林资源总的变化趋势是:森林面积逐年增加,每年以200万hm2速度递增,林木生长量开始大于消耗量,森林资源的发展在数量上开始走出“低谷”,扭转了长期以来森林资源下降的局面,实现了森林面积和森林蓄积的“双增长”。森林资源是决定林业生存和发展的基础。森林资源的发展对我国的经济起到了至关重要的作用,所以,林区的整地、造林方法就显得尤为重要,本文主要论述了在实际工作中常用的一些造林方法。  相似文献   

7.
在当前我国社会经济发展的过程中,森林资源的开发利用有着十分重要的意义,它是我国国民经济增长的重要内容之一。因此我们在林业发展的过程中,就要采用相应的保护城市,来对其森林资源进行保护。而且近年来随着造林范围的不断扩大,人们对森林资源的保护意识也在不断的增强,因此就将传统的森林防火工作进行相应的改进和完善,从而使其可以对整个森林系统的安全性和可靠性得到有效的保障,有效的避免了森林火灾给人们带来的巨大损失。本文通过对现阶段森林防火工作管理政策进行简要的概述,讨论了森林防火工作措施的相关内容,以供参考。  相似文献   

8.
在全球环境不断恶化的新背景下,加强森林资源的保护意义重大。森林资源的保护是一项重大的生态工程,关系到国家经济的可持续发展。本文作者就搞好森林资源的保护从四个方面进行了简要的论述:国家林业主管部门要加强管理,加强森林病虫害的防治,抓好森林防火工作,提高思想认识。  相似文献   

9.
生态环境的恶化,对我国社会经济发展造成了较大影像。森林是维护生态安全的重要屏障。因此,加强林业有害生物防治工作是保护森林资源安全,保护生态坏境的重要措施。本文对佳木斯地区林业有害生物防治工作进行了调查,并提出了解决问题的途径。  相似文献   

10.
浅谈植树造林的方法   总被引:4,自引:0,他引:4  
我国森林资源总的变化趋势是:森林面积逐年增加,每年以200万hm2速度递增,林木生长量开始大于消耗量,森林资源的发展在数量上开始走出"低谷",扭转了长期以来森林资源下降的局面,实现了森林面积和森林蓄积的"双增长"。森林资源是决定林业生存和发展的基础。森林资源的发展对我国的经济起到了至关重要的作用,所以,林区的整地、造林方法就显得尤为重要,本文主要论述了在实际工作中常用的一些造林方法。  相似文献   

11.
This report proposes a method of estimating the amount of safety stock needed in each station of a production line due to variation in processing times, machine breakdowns and demand fluctuation in order to meet a predetermined desired level of performance. The production line is assumed to operate as a pull system and the measure of performance is the average percentage of demand backlogged. Multiple machines and different batch sizes in the stations are included in the model. Dynamic production control is used and is based on the current inventory level in every station of the system. Simulation results are used to test the performance of the system in which the maximum inventory level allowed in each station is based on the estimation given by our method.  相似文献   

12.
具有自消化引擎的库存模型是与传统库存完全不同的库存模型.自消化引擎库存是指库存系统具有内循环需求引擎、库存物资具有自修复能力以及寿命递减等生命库存的特征,库存的保有量与物资的用途、使用方法、技术定义、管理模式以及外部变化或扰动等密切相关.本文提出自消化引擎这一概念来描述这类库存的模型特征,并对这类库存模型的相关特征进行了讨论和初步研究.  相似文献   

13.
简要介绍了工程选线、选址勘测中遥感技术的应用概况;阐述了工程地质遥感技术应用的特点,认为工程地质遥感技术应用有别于其他领域;强调了我国工程地质遥感技术应用与其他国家不同,形成了我国自己的应用特点,这些特点是由我国国情决定的;探讨了工程地质遥感技术应用的若干问题,包括遥感图像判释,遥感图像处理、数据综合分析、施工阶段遥感技术应用等。  相似文献   

14.
In this paper, we consider a multiple-stage tandem production/inventory system producing a single product. Processing time at each stage is assumed to have a general stationary processing time distribution. The cost of holding work-in-process (WIP) inventory is different at each stage. Therefore, decisions on when to release work to the system as well as when to transfer WIP from one stage to another need to be made. We formulate this problem of release/production control as a Markov decision process. However, the optimal policy is rather complex, making its implementation impracticable in practice. We therefore investigate the performance of simple base stock policies. Our approach aggregates several stages into one and uses a simple approximation to compute 'approximately optimal' base stock levels. We present the results of a simulation study that tests the performance of our approximation in estimating the best base stock levels, and the performance of base stock policies as compared with the optimal policy.  相似文献   

15.
当库存物资呈现寿命递减,并具有自修复能力或变异吸收等生命特征时,基于传统库存模型的相关理论已不能给予客观解释.本文根据刀具生命库存成本模型,以计划期内总成本最小为目标函数,得到模型在理想稳定状态下新刀具最优经济订货批量和最优修复能力的数学模型.结果表明,基于生命特征的库存模型可以更准确表现实际库存的状态;库存修复能力直接影响库存成本的变化,而传统库存模型只是经济生命库存模型中无生命特征的一个特例.  相似文献   

16.
海洋光学遥感技术的发展和前沿   总被引:13,自引:0,他引:13  
空间遥感与信息技术已经发展成为满足人类对海洋资源和环境不同尺度和不同层次连续、动态的信息需求的必要手段。海洋光学遥感在实施大范围海面瞬间信息监测、数年至几十年长序列全球海洋数据采集等方面,发挥了常规调查方法所不能替代的优势。从20世纪70年代开始,国际上发展了利用测量离水辐射率的原理,用现代的卫星遥感技术来实时监测海洋水色环境。80年代以来,我国对该项高技术也十分重视,并有了长足进展。文章回顾我国近20年来海洋光学遥感技术的发展;讨论了当前国家在海洋权益、防灾减灾、海洋资源管理和开发等方面的进一步需求;论述了该技术在环境监测应用导向下的前沿,如:高精度分析和定量化、高频率长序列监测和业务化趋向、多平台监测数据同化和核心技术合成。  相似文献   

17.
In periodic review inventory systems, inventory is classified into cycle stock and safety stock. Cycle stock is defined as inventory that absorbs differences between supply and demand frequencies. It can be calculated without deficiency or excess because a method has been established for ensuring that the minimum on-hand inventory during a periodic review is zero. Safety stock is defined as inventory that absorbs various differences between supply and demand. Unlike for cycle stock, a method for calculating safety stock without deficiency or excess remains to be established. An approach is proposed to establishing a method for calculating inventory in which inventory is classified on the basis of the holding purpose and the calculation factors indicate solutions. This approach was applied to inventory held to absorb, on the basis of fluctuations in demand, the difference in terms of time and quantity between supply and demand. Stock held for this purpose is referred to as ‘fluctuation stock’. The objective is to establish a method for calculating fluctuation stock so that the minimum on-hand inventory during a periodic review is zero and to clarify the relationship between fluctuation stock and safety stock.  相似文献   

18.
A single-stage production-inventory system produces parts in a make-to-stock mode, and unsatisfied demand is backordered. The system operates under a so-called base stock with WIP cap replenishment policy, which works as follows. Whenever the Work-In-Process (WIP) plus finished goods inventory falls below a specified level, called base stock, a replenishment order for the production of a new part is issued. If the WIP inventory is below a different specified level, called WIP cap, the order goes through and a new part is released for production; otherwise, the order is put on hold until the WIP inventory drops below the WIP cap. First, it is shown that the optimal base stock that minimizes the long-run, average, inventory holding cost for a given minimum customer service level, is a non-increasing function of the WIP cap that reaches a minimum value, called minimum optimal base stock, at a finite WIP cap value, called critical WIP cap. Then, it is shown that the optimal WIP cap is less than or equal to the critical WIP cap and therefore the optima! base stock is greater than or equal to the minimum optimal base stock. More interestingly, however, it is conjectured that the optimal WIP cap is in fact exactly equal to the critical WIP cap and therefore the optimal base stock is exactly equal to the minimum optimal base stock. The minimum optimal base stock is none other than the optimal base slock of the same system operating under a classical base stock policy (with no WIP cap). Finally, the optimal parameters of a system operating under a base stock with WIP cap policy are related to the optimal parameter of the same system operating under a make-to-stock CONWIP policy.  相似文献   

19.
Most of the works on multi-objective inventory control unify the various objectives into a single objective such that lead to a compromise solution whose non-dominance is not guaranteed. This paper presents an algorithm based on Electromagnetism-like Mechanism (EM) to solve a multi-objective inventory control problem with cost and shortage minimization objectives. EM is a new meta-heuristic originated from the electromagnetism theory in physics; it simulates attraction and repulsion of charged particles in order to move towards the optimum. A framework, so called Multi-Objective EM (MOEM), is proposed to approximate the well-known efficient solutions of order size and safety stock without using any surrogate measure (e.g. service level or shortage cost) and prior preference information from decision-makers. To give a specific compromise solution, any outranking method can be implemented to prioritize the non-dominated solutions for decision-makers. Finally, this could be the first attempt to apply EM to multi-objective inventory control, even the inventory control problems.  相似文献   

20.
微波遥感若干前沿技术及新一代空间遥感方法探讨   总被引:6,自引:0,他引:6  
随着微波遥感技术在国民经济发展、环境和灾害监测、资源勘探、科学研究以及军事中应用的不断深入,这一技术正在经历着前所未有的发展。文章就当前微波遥感发展的若干前沿技术,例如高性能和新型机理、更高频率的开拓、全电磁波综合探测、小型化以及虚拟探测等进行了分析论述,重点介绍了三维成像雷达高度计、干涉式综合孔经微波辐射计以及虚拟探测技术。最后介绍了全球地形测量编队小卫星的设想。  相似文献   

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