系統是什嗎？

系統是什嗎？摘自《FUNDAMENTALS OF PHYSICAL GEOGRAPHY (2nd Edition)》
BY ？ 劉建文略譯（http://blog.csdn.net/keminlau
）

KEY: 科學哲學 系統 系統理論 模型

系統與模型

(a). Humans and Their Models

One common conclusion of scientific inquiry（質詢; 調查 ） is that the world of nature is often very complex. To understand this complexity, scientists usually try to envisage（想像, 設想;） the phenomena of nature as simplified versions of reality known as a system. A system can be defined as a collection of interrelated parts that work together by way of some driving（精力旺盛的; 強勁的; 驅使的 ） process.

我們對自然界進行研究的一個常見的結論就是，自然界是很複雜的。為了把握這些複雜性，科學家通常把自然現象假想成一種簡化過的實在（reality），它就是我們常常聽到的“系統”。“系統”可以被定義成相關部分（或者叫子系統）的集合，這些子部分在某種驅束力下工作在一起。

In the world of science, the word model is quite similar in meaning to the term system. Models in science tend to be simplified representations of reality that can be explained of mathematically and through the use of graphics. The following graphical model is used to help explain the processes involved in scientific understanding. The arrows in this graphically model suggest a continuous interaction between perceptible（可察覺的, 看得見的） phenomena and theory through the processes of explanation and validation. This simple graphical model, while an extreme abstraction of the real world, is quite useful in explaining how scientific understanding works.

在科學的世界裡，“模型”一詞與“系統”有十分相似的意思，只是二者偏重有點不一樣。模型偏向於簡化實在的表徵，從而有助於數學地或圖形化地對實在進行解釋（explained）。比如下面的圖形模型，它是用來協助解釋科學認識（scientific understanding）的過程的模型。在這幅生動的模型圖中，箭頭有形地展示（suggest）了透過解釋和驗證的過程在理論（theory）與現象（phenomena）之間存在的連續不斷的互動。這也是科學認識的本質過程。這幅相當抽象的構圖很簡單，但對於解釋科學認識的原理很有用。

KEMIN：沒有講“系統”偏向簡化實在的什麼東西。

Figure 4a-1: The general relationship between perceptible phenomena and theory using scientific method for understanding. The interaction between perceptible phenomena and theory is arrived at through the processes of explanation and validation.

In Physical Geography, and many other fields of knowledge, systems and models are used extensively as aids in explaining natural phenomena around us.

在各知識領域裡，系統和模型被廣泛地用來輔助解釋我們身邊的各種自然現象。

系統的定義

(b). Definitions of Systems and Models

As suggested in the previous section, a system is a assemblage of interrelated parts that work together by way of some driving process (see Figure 4b-1). Systems are often visualized or modeled as component blocks that have connections drawn between them. For example, the illustration below describes the interception（攔截; 截擊; 截取;） of solar radiation（太陽輻射） by the Earth. In this system, the Earth and Sun, the parts or component blocks, are represented by two colored circles of different size. The process of solar emission（發射） and the interception of the Sun's emitted radiation by the Earth (the connection) is illustrated by the drawn lines.

前面談到，系統是一組相關部分的集合，並且這些子部分在某種驅束力下一起工作。系統常常被可視化或模型化為多個組件塊，並且在這些組件塊之間用線連起來表示它們的關係。比如如下的關於太陽輻射的模型圖：

Figure 4b-1: Simple visual model of solar radiation being emitted from the Sun and intercepted by the Earth.

Most systems share the same common characteristics. These common characteristics include the following:

大多數系統都擁有一些通用的性質，包括如下的：

• 1. Systems have a structure that is defined by its parts and processes.
• 2. Systems are generalizations of reality.
• 3. Systems tend to function in the same way. This involves the inputs and outputs of material (energy and/or matter) that is then processed causing it to change in some way.
• 4. The various parts of a system have functional as well as structural relationships between each other.
• 系統都是有一定的結構，由組成部分和作用（processes）定義；
• 系統都是對實在（reality）的一般化（generalizations ）；
• 系統都有同樣的表現作用的方式，作用過程包括物質和能量的輸入與輸出，由輸入到輸出，物質和能量會以某一種方式被改變或轉換；
• 系統內部各部分都有功能依賴和結構制約關係；
• 5. The fact that functional relationships exist between the parts suggests the flow and transfer of some type of energy and/or matter.
• 6. Systems often exchange energy and/or matter beyond their defined boundary with the outside environment, and other systems, through various input and output processes.
• 7. Functional relationships can only occur because of the presence of a driving force（驅動力，張力）.
• 8. The parts that make up a system show some degree of integration - in other words the parts work well together.
• 系統內兩部分間有功能關係意味著它們之間存在著某種能量和物質的流動和傳輸；
• 系統通常會與定義它的邊界以外的環境（包括其它系統）進行能量或物質交換；
• 功能關係只源於某種驅動力或張力的存在；
• 系統內的各部分表現出一定的整合程度，並且系統整體大於部分之和。

  KEMIN:最後一點原文不好理解；還有這裡能量和物質還沒有進一步解開。

Within the boundary of a system we can find three kinds of properties:

Elements - are the kinds of parts (things or substances) that make up a system. These parts may be atoms or molecules（分子; 些微）, or larger bodies of matter like sand grains, rain drops, plants, animals, etc.

Attributes - are characteristics of the elements that may be perceived（察覺; 意識到; 感知; 理解） and measured. For example: quantity, size, color, volume, temperature, and mass.

Relationships - are the associations that occur between elements and attributes. These associations are based on cause and effect.

在系統的邊界內我們可找到三類屬性：

元素（Elements）：組成系統的各種部分（東西或事物）。這些系統部分可能是原子性，也可能是非原子性，比如子系統；

屬性（Attributes）：指被丈量或感知的系統元素的特性（characteristics）；比如數量、大小、顏色、容量、溫度和規模；

關係（Relationships）：指在元素和屬性之間存在的某種結合（associations），這些結合是基於因果關係的。

We can define the state of the system by determining the value of its properties (the elements, attributes, and/or relationships).

我們可以根據這三類屬性的值（value）來定義或描述一個系統（的狀況）。

系統的分類

Scientists have examined and classified many types of systems. Some of the classified types include:

Isolated System - a system that has no interactions beyond its boundary layer. Many controlled laboratory experiments are this type of system.

Closed System - is a system that transfers energy, but not matter, across its boundary to the surrounding environment
. Our planet is often viewed as a closed system.

Open System - is a system that transfers both matter and energy can cross its boundary to the surrounding environment. Most ecosystems生態系統 are example of open systems.

Morphological（形態學的; 形態的） System - this is a system where we understand the relationships between elements and their attributes in a vague sense based only on measured features or correlations. In other words, we understand the form or morphology a system has based on the connections between its elements. We do not understand exactly how the processes work to transfer energy and/or matter through the connections between the elements.

Cascading System - this is a system where we are primarily interested in the flow of energy and/or matter from one element to another and understand the processes that cause this movement. In a cascading system, we do not fully understand quantitative relationships that exist between elements related to the transfer of energy and/or matter.

Process-Response System - this is a system that integrates the characteristics of both morphological and cascading systems. In a process-response system, we can model the processes involved in the movement, storage, and transformation of energy and/or matter between system elements and we fully understand how the form of the system in terms of measured features and correlations.

Control System - a system that can be intelligently manipulated by the action of humans.

Ecosystem - is a system that models relationships and interactions between the various biotic and abiotic components making up a community or organisms and their surroundng physical environment.

能量與環境

An environmental system can be defined as a system where life interacts with abiotic factors. All environmental systems involve the capture, movement, storage, and use of energy. This fact also makes them energy systems. Energy is captured in the living components of environmental systems by processes like photosynthesis, biomass consumption, and biotic decomposition. Energy is also used in environmental processes that are strictly abiotic. For example, solar energy is responsible for wind, weathering, and precipitation.

平衡與反饋

Equilibrium can be defined as the average state of a system as measured through one of its attributes or elements. Scientists have defined six different types of equilibrium. Most systems maintain a steady state equilibrium through the operation of positive and negative feedback mechanisms. Negative-feedback mechanisms control the state of the system by dampening or reducing the size of the system's elements or attributes. Positive-feedback mechanisms feed or increase the size of one or more of the system's elements or attributes over time. This section concludes by showing how negative and positive feedbacks work to cause fluctuations in the population size of aphids.