Two Patterns of Evolution for Technological Systems

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    By Kai Yang and Hongwei Zhang


    Studying the patterns of technological evolution is important for predicting future technology development and for guiding product development. There are many patterns of evolution. In this paper, the authors discuss two frequently encountered patterns: transition to a high-level system and increasing ideality. The details are analyzed through practical examples.


    Before Theory of Inventive Problem Solving (TRIZ) technology was developed, the main method for solving inventive problems in engineering as well as other areas of human activities was trial and error. Trial and error relies on the engineer's educational background or their own limited experience for solving invention problems. It is inefficient and impractical to apply in fiercely competitive environments.

    After researching hundreds of thousands of patents, Genrich Altshuller and his colleagues developed TRIZ, which concluded that the evolution of technological systems is governed by several patterns and lines. Where lines are sub-patterns under a major pattern. These patterns or lines can be employed for predicting the conscious development of technological systems (problem solving) and replacing the inefficiencies of blind searching. Altshuller summarized these patterns or lines of evolution as follows:1

    There are two important patterns, transition to high-level system and increasing ideality.

    Transition to a Higher Level System

    A lot of patents demonstrate that if an engineering system is a mono-system (in terms of functional properties) it evolves by changing it to a bi-system. If it is a bi-system, it evolves by changing it to a poly-system.

    A mono-system is defined as a single object with one function. Take for example a knife, a one-barrel hunting rifle (as far as the barrel system is concerned) and a telescope (as far as the optical system is concerned). A bi-system is defined as the combination of two sub-systems whose functions or properties are identical or similar or different or opposite. A poly-system is defined as the combination of three or more sub-systems whose functions or properties are identical or similar or different or opposite. Transition to a higher-level system is an important evolution trend. Classifying and investigating this trend helps predict the next product generation.

    Bi-system, Transited from a Mono-system

    Based on the functional properties transited from a mono-system, bi-systems can be classified into two catalogs: single function bi-system and multi-function bi-system. These two catalogs are further divided as homogeneous, shifted, heterogeneous and an inverse system. Figure 1 illustrates the classification scheme combining two mono-systems into one bi-system where it can enhance functional performance of each constitutive sub-system and develop new and useful functional properties.

     Figure 1: Classification of a Bi-system

    Single Function Bi-system

    A single function bi-system is the combination of two mono-systems and it has the same function as the two sub-systems; however, its performance is improved. If sub-systems have identical functional properties, a homogeneous bi-system is developed. If sub-systems have similar functional properties, a shifted bi-system is developed.

    Examples of a homogeneous bi-system include:

    Examples of a shifted bi-system include:

    Multi-function Bi-systems

    A multi-function bi-system combines functions of two sub-systems into one system and the performances, structures and other properties are improved. A multi-function bi-system is constructed by composing:

    1. Two sub-systems whose functions are different but relatively compatible. A heterogeneous bi-system is developed.
    2. Two sub-systems whose functions are opposite. An inverse bi-system is developed.

    Examples of a heterogeneous bi-system can be found in the U.S. patent database.

    Inverse bi-systems are also easy to find, for example:


    A poly-system is defined as the combination of three or more sub-systems whose functions or properties are identical or similar or different or opposite. Based on the functions of poly-systems an individual can classify them into two catalogs: single function poly-systems and multi-function poly-systems. These two catalogs are further divided as shown in Figure 2. Combining three or more sub-systems into one can enhance functional performance of each constitutive sub-system and develop new and useful functional properties.

     Figure 2: Classification of a Poly-system

    Single Function Poly-system

    A single function poly-system has the same function as a sub-system, however, its performances and properties are improved. A single function poly-system is constructed by composing:

    1. Three or more identical sub-systems. A homogeneous poly-system is developed.
    2. Three or more similar sub-systems. A shifted poly-system is developed.

    Examples of a poly-system can also be found in the U.S. patent database. Examples of a homogeneous poly-system include:

    Examples of a shifted poly-system are also found in many cases, examples include:

    Multiple-function Poly-system

    A multi-function poly-system combines all sub-system functions into one system and the performances, structures and other properties are improved in this way. A multi-function poly-system is constructed by composing:

    1. Three or more sub-systems whose functions are different but relatively compatible. In this way, a heterogeneous poly-system is developed.
    2. Three or more sub-systems whose functions are opposite (at least two functions are opposite). In this way, an inverse poly-system is developed.

    Examples of a heterogeneous poly-system include:

     Figure 3: A Folding
     Pocket Tool

    Examples of an inverse poly-system include:

    Simplification of Bi- and Poly-systems

    Bi- and poly-systems are further enhanced by simplification. Eliminating auxiliary components results in partial simplification and further work results in a completed simplification, which means a poly-system becomes a mono-system again.

    Examples of a partially simplified bi- and poly-system include:

    A completely simplified bi- and poly-system results in a new mono-system. Examples include:

    Increasing Ideality: Several Principles to Ideal Design

    Another important pattern, increasing ideality, states that evolution of all technological systems proceeds in the direction of increasing the degree of ideality. This means that in the process of evolution either the system performing a certain function gets less cost or the system becomes capable of performing its function better or performing more functions than for which it was originally designed. Ideality is defined as the sum of a system's useful functions divided by the sum of its undesired effects.4

    Ideality = All Useful Effects
                 All Harmful Effects 

    Ideality is the benefit-to-cost ratio. When using this ratio to evaluate the progress of a technological system, one should keep in mind that it is "vertical," not "horizontal," concepts. This means an individual may use the ratio to express the ideality of one technological system, but not to compare different technological systems. For example, using the ratio to compare the ideality of television sets and refrigerators means nothing because the definitions of useful function and harmful function are different. Ideality has the same properties of quality cost. Quality cost is used to improve the direction of a company's management system. It is strongly suggested, however, that quality cost should not be used to benchmark the quality performance of different companies because definitions and classifications of quality costs could have many differences.

    The ideality is a general measure of system excellence. Ideality is a global concept, but the solutions to accomplish an excellent ideality are dependent on specific situations faced by different technological systems and development tasks. For example, for a high cost product such as automotive products, it is important to deliver needed functions reliably without increasing cost; for an electronic consumer product, rapidly adding advanced features with a low cost increase might be a better strategy. The following principles are useful in helping to find specific approaches in achieving the ideal final solution based on different situations.

    Realizing the Ideal System: Desired Functions are Achieved Without a System

    In an engineer's point of view, any technological system is not a goal in itself and is needed only to perform a special function. To realize the desired function is an engineer's final goal. The better system is the one that consumes fewer resources in both initial construction and maintenance. Thus, the ideal system requires no material to be built, consumes no energy and space, needs no maintenance and cannot be broken.3 It appears that this kind of system is only in our imagination, but it is true that there are some cases when the ideal system concepts can be fully realized. The following are two examples.

    Example 1: Cultivating fishes in farmland.6

    The Southeast part of China has a high density population. Every piece of land is used to raise rice; therefore, no extra space is used to cultivate fish. In order to solve fish shortage problems, agriculture experts suggest that the farmland be used to cultivate fish while it is used to cultivate rice. The experiments were successful. In this case, farmers use the land and water (resources) to cultivate rice and fish. The wastes of fish are used as fertilizer for rice. The desired function, cultivating fish, is realized without a fish raising system.

    Example 2: Lamps without bulbs.2

    During the 1970s, the Soviet Union launched an unmanned lunar probe to the moon's surface to transmit television pictures to the Earth. A projector using a light bulb was designed to illuminate the lunar surface ahead of the vehicle. Existing light bulbs, however, would not survive the impact of landing on the moon's surface. The most durable bulbs were ones used in military tanks, but even those bulbs would crack at the joint between the glass and screw base during tests. A new bulb design suitable for the application had to be developed. The situation was reported to the program leader, Dr. Georgi Nikolayevich Babakin, a researcher and radio specialist, who asked: "What is the purpose of the bulb?" The answer was obvious, to vacuum seal around the filament. The moon's atmosphere, however, presents a perfect vacuum. Therefore, Babakin suggested lamps without bulbs.

    Obtaining an Ideal System: Desired Functions are Ideally Performed by Already Existing Substance Resources

    Resources are substances, fields, field properties, function characteristics and other attributes existing in a system and its surroundings, which are available for system improvement.1 In order to obtain an ideal system or to increase ideality of a system, all resources should be considered, but a substance resource is one that is used a lot. Substance resources can be divided into several categories. Readily available substance resources are ones that can be used in their existing state. Derived substance resources are resources that can be used after some kind of transformation. Since substance resources include all material from which the system and its surroundings are composed, any system that has not reached its ideal state should have substance resources available.

    Example 3: Use the equipment to replace the ballast.

    Late in the space program to the planet Venus, an influential scientist wanted his ten kilogram experiment to be included on the voyage. He was told that it was too late because every gram already had been identified. Not accepting this answer, he identified 16 kilograms of ballast. He then proposed the removal of ten kilograms to be replaced with his equipment. In this case, the ballast was the unidentified resource.

    Example 4: Using a pollutant (waste) to prevent pollution.

    To prevent pollution, exhaust gas from a thermal power station is treated with alkaline chemicals. The alkaline slag is recovered from coal burning at a coal power station. Where the slag had also been a source of pollution. In this case, the system function of preventing pollution is realized by using an existing resource.

    Obtaining and Approximating the Ideal System: Desired Functions are Obtained by Using Physical, Chemical and Geometric Effects Without Costs

    There are two ways to increase system ideality. The first is to increase the number or magnitude of the useful functions; the second is to reduce the cost, number or magnitude of the harmful functions. Often a complex system is replaced with a simple one if a physical, chemical and geometric effect is used. The system ideality, therefore, can be improved in this way.

    Example 5: Reinforcing a rod.5

    Reinforcing rods are stretched before pouring concrete during the manufacturing of pre-stressed concrete slabs. A hydraulic system uses the coefficient of thermal expansion by heating the rods, which causes them to expand. The rods are then clamped into position and allowed to cool.

    Example 6: Ferromagnetic powder throttle.5

     Figure 4: Ferromagnetic Particles

    A disadvantage of throttles with electromagnetic control, containing a magnetically controlled valve that shuts off the air duct, is the complexity and inadequate reliability of their design. Using ferromagnetic effects can solve this problem. The valve is formed as ferromagnetic powder is controlled by the magnetic field and placed between the nets in the air duct.

    Obtaining and Approximating the Ideal System: Desired Function is Realized by Excluding Auxiliary Functions

    Auxiliary functions provide support for and/or contribute to the execution of the main function. In many situations, auxiliary functions may be excluded (together with the elements and/or parts associated with their performance) without deteriorating the performance of the main function.

    Example 7: Painting without solvents.

    Painting metal parts with conventional paint releases dangerous fumes from the paint solvents. An electrostatic field can be used to coat metal parts with powder paint. After the powder is applied, the part is heated and the powder melts. A finished coat of paint is then produced without solvents.

    Example 8: Self-feeding liquid.

    A pump feeds colored liquid to a clearance area between transparent plates in the roof of a greenhouse, forming a thin translucent sheet. The clearance thickness and opacity of the liquid sheet serve to control solar radiation entering the greenhouse. The function is okay but the hydraulic equipment increases the cost of the greenhouse.

    In order to reduce costs, it is proposed to eliminate the hydraulic system. An expandable liquid is placed in the roof cavity. As the temperature inside the greenhouse rises, the liquid expands. The roof cavity becomes filled with fluid, preventing solar energy from entering the greenhouse. The auxiliary function (the hydraulic equipment) is eliminated and the cost of the whole technological system is reduced.

     Figure 5: Old Greenhouse Design

     Figure 6: New Greenhouse Design

    Obtaining and Approximating the Ideal System: Desired Functions are Realized by Using Self-service Functions

    Self-service means that the object carries out supplementary and auxiliary operations with the means used for the primary useful function. Self-service makes use of wasted material and energy. Self-service of an object allows efficient action and better use of the internal object resource.

    Example 9: Gas bearing.

    A pump supplies gas to the internal cavity of a sliding bearing. The gas provides bearing strength by passing through a porous insert to the small clearance between the bearing and the shaft. The disadvantage of this system is that the pump restricts the applicable range of the bearing. In order to overcome this shortcoming, it is proposed to eliminate the pump. Cobalt and nickel hydrides are placed in the bearing's internal cavity. While heating, they release hydrogen gas, which enters the working clearance and provides bearing strength. When cooled, the hydrides re-absorb hydrogen gas. This reduces gas loss during bearing operation.

     Figure 7: Old Gas Bearing Design

     Figure 8: New Gas Bearing Design

    Example 10: Using the specimen as the container.

    To study the effects of acids on metal alloy, specimens are placed into a hermetically sealed chamber. The chamber is filled with acid, then closed and the various combinations of temperature and pressure are created inside. The acid is not only reacting with the specimens but also with the walls of the chamber. To protect the walls, they are glass-coated. However, this solution is costly. The ideal design has a specimen exposed to the acid without requiring the use of a container. The transformed problem is to find a way to keep the acid in contact with the specimen without a container. The solution is to make the container out of the specimen.


    The Theory of Inventive Problem Solving offers a wide-range series of tools and methods to help designers and inventors solve problems in creative and powerful ways. Patterns of evolution constitute the theoretical foundation of these techniques. Among these patterns, increasing ideality and transition to a high level are two of the most important ones.

    Previously, the transition to a high-level system was considered the final evolution stage of a system. It was assumed that the system potential be exhausted on its own level first, after which it is transformed to the high-level system. Several examples in this paper have confirmed that this transition can happen at any stage of evolutions and a low-level system may exist in some circumstances even though a high-level system has been developed.

    There are several ways or principles to increase ideality of a technology system. Any principle proposed in this paper may be applied to eliminate the deficiencies of the original system, to preserve or enhance the advantages of the original system and to simplify the system. 


    1. G.S Altshuller, Creativity as Exact Science, Gorden & Breach, New York, 1984.
    2. G.S Altshuller, And Suddenly the Inventor Appeared, Technological Innovation Center, 1996.
    3. V.R. Fey and E.I Rivin, The Science of Innovation, TRIZ Group, 1997.
    4. John Terninko, Alla Zusman and Boris Zlotin, Systematic Innovation: An Introduction to TRIZ, CRC Press LLC, 1998.
    5. Invention Machine Lab 2.11, 1995–1996.
    6. Kai Yang and Basem S. El-Haik, Design for Six Sigma: A Road Map for Product Development. McGraw Hill Professional, 2003.

    About the Authors:

    Kai Yang, PhD is a professor at the Department of Industrial and Manufacturing Engineering at Wayne State University. Contact Kai Yang at ac4505 (at) or visit

    Hongwei Zhang is a graduate student at Wayne State University. Contact Hongwei Zhang at hwzhang (at)

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