Adonis Diaries

Posts Tagged ‘experimental

Article 33

 “How to tell long and good stories from human factors graphs?”

If we concentrate on a graph we might generate a long story that span many disciplines and furnish us with a wealth of information and knowledge that pages of words cannot convey. A graph might open the gate for dozen of questions that are the foundation of scientific, experimental, and critical thinking.  Suppose that we are comparing the efficiency in energy consumption between walking bare feet or wearing shoes that weight 1.3 Kg.  Considering the walking speed as the other independent variable along with the type and weight of shoes then we observe that the curves show that we are consuming less energy at low speed, then both curves decreasing to a minimum consumption of 0.2 KJ/Nm and intersecting at around 80 meter/min and then increasing as walking speed increases.

This graph is telling us that casual walking consumes less energy per unit walking effort than fast walking and that at a cut off speed of 80 meter/min the energy consumption is equal for both foot wares.  Some people might jump to the conclusion that this cut-off speed can be generalized to all foot wears but more experiments are necessarily needed to verify this initial hypothesis.  Another piece of information is that after the cut-off speed it is more economical energy wise to walk barefoot. Basically, this graph is saying that the more weight you add to your lower limbs the more energy you should expect to spend, a fact that is not an earth shattering observation. Biomechanics tells us that the structure of our body is not geared toward saving on our muscular effort but to increasing our range and speed of movements.  Most of our muscles are connected to the bones of our limbs and their respective joints in manners they have to exert great effort and many fold the weight of our body members to overcome any of our limb’s mass.  Usually, the tendons of our muscles are inserted to the limb bones close to the joints and thus the muscles have to exert a huge effort to overcome the moment of the bone and flesh weight in order to effect a movement. Any extra mass to our limbs will tax our muscles to produce many folds the additional weight.

There is a caveat however; if you wrapped a weight of 1.3 kg around your ankles and walked bare feet you would consume more energy than without the added weight but the curve would be parallel to the previous curve and not increasing more steeply than walking with shoes weighting 1.3 Kg.  Consequently, the variation in the behavior of the graphs result from a combination of added weight and lesser static coefficient of friction exerted by the shoes on the walking surface than the bare foot..

Thus, what this graph does not mention is the static coefficient of friction between the footwear and the ground and which is the most important variable and in this case can concatenate many independent and control variables such as the materials of the footwear and the type of ground into a unique independent variable of coefficient of friction.  The higher the coefficient of friction the easier it is to move and progress and thus walking faster for the same amount of effort invested.  It is not that important to generate muscle force if the reaction force on the surface cannot be produced to move a person in the right direction; for example, it is extremely difficult to move on slippery surfaces no matter how much muscular effort we generate.  Apparently, the shape and skin texture of our foot provide a better and more efficient coefficient of friction than many foot wears.

However, the most important fact of this simple experiment is showing us the behavior of the curves and offering additional hypotheses for other studies.

What this graph is not telling us is the best story of all and which can excite the mind into further investigation. For example, what kind of earth materials are we walking on; sands, asphalt, rough terrains, slippery roads or grassy fields?  Does the sample of bare feet walkers include aboriginals used in walking bare feet, city dwellers, and people from the province?  Does the sample groups people according to the softness of their feet skins or the size of feet?

May be the shape of the curves are the same for females as well but it would be curious to find out the magnitude of variations compared to males.  It is clear that a simple and lousy graph delved us into the problems of experimentation and raised enough questions to attend to various fields of knowledge.

In the final analysis, the question is how relevant is this experiment practically?  How far can a modern man walk bare feet?  Does any economy in energy compensate for the ache, pain and injuries suffered by walking bare feet?  Would athletes be allowed to compete bare feet if it is proven to increase performance and break new records?  Does anyone care of walking barefoot in order to save a few kilo Joules?

The theme of this article is that you can venture into many fields of knowledge just by focusing your attention on graphs and tables and permitting your mind to navigate into uncharted waters through queries and critical thinking.


Article “31 (December 18, 2005)

 “A seminar on a multidisciplinary view of design”  

The term “designing” is so commonly used that its all encompassing scope has lamentably shrunken in the mind of graduating engineers. This talk attempts to restore the true meaning of design as a multidisciplinary concept that draw its value from the cooperation and inputs of many practitioners in a team.

This is a scenario of a seminar targeting freshmen engineers, who will ultimately be involved in submitting design projects, is meant to orient engineers for a procedure that might provide their design projects the necessary substance for becoming marketable and effective in reducing the pitfalls in having to redesign. The ultimate purpose is to providing the correct designing behavior from the first year.

Answering the following questions might be the basis of acquiring a proper behavior in design projects, which should be carried over in their engineering careers.  Many of these questions are never formally asked in the engineering curriculum.

Q1. What is the primary job of an engineer?   What does design means?  How do you perceive designing to look like?

A1. The discussion should be reopened after setting the tone for the talk and warming up the audience to alternative requirements of good design.

Q2. To whom are you designing?  What category of people? Who are your target users? Engineer, consumers, support personnel, operators?

A2. Generate from audience potential design projects as explicit examples to develop on that idea.

Q3. What are your primary criteria in designing?  Error free application product? Who commit errors?  Can a machine do errors?

A3.  Need to explicitly emphasize that error in the design and its usage is the primary criterion and which encompass the other more familiar engineering and business criteria

Q4. How can we categorize errors?  Had you any exposure to error taxonomy? Who is at fault when an error is committed or an accident occurs?

A4. Provide a short summary of different error taxonomies; the whole administrative and managerial procedures and hierarchy of the enterprise need also to be investigated.

Q5. Can you foresee errors, near accidents, accidents in your design?

A5. Take a range oven for example, expose the foreseeable errors and accidents in the design, babies misuse and the display and control idiosyncrasy.

Q6. Can we practically account for errors without specific task taxonomy?

A6. Generate a discussion on tasks and be specific on a selected job.

Q7. Do you view yourself as responsible for designing interfaces to your design projects depending on the target users? Would you relinquish your responsibilities for being in the team assigned to designing an interface for your design project? What kinds of interfaces are needed for your design to be used efficiently?

A7. Discuss the various interfaces attached to any design and as prolongement to marketable designs.

Q8. How engineers solve problems?  Searching for the applicable formulas? Can you figure out the magnitude of the answer?  Have you memorized the allowable range for your answers from the given data and restriction imposed in the problem after solving so many exercises? Have you memorize the dimensions of your design problem?

A8.  Figure out the magnitude and the range of the answers before attempting to solve a question; solve algebraically your equations before inputting data; have a good grasp of all the relevant independent variables.

Q9. What are the factors or independent variables that may affect your design project? How can we account for the interactions among the factors?

A9. Offer an exposition to design of experiments

Q10. Have you been exposed to reading research papers? Can you understand, analyze and interpret the research paper data? Can you have an opinion as to the validity of an experiment? Would you accept the results of any peer reviewed article as facts that may be readily applied to your design projects?

A10.  Explain the need to be familiar with the procedures and ways of understanding research articles as a continuing education requirement.

Q11. Do you expect to be in charged of designing any new product or program or procedures in your career? Do you view most of your job career as a series of supporting responsibilities; like just applying already designed programs and procedures?

Q12. Are you ready to take elective courses in psychology, sociology, marketing, business targeted to learning how to design experiments and know more about the capabilities, limitations and behavioral trends of target users? Are you planning to go for graduate studies and do you know what elective courses might suit you better in your career?

A12.  Taking multidisciplinary courses enhances communication among design team members and more importantly encourages reading research papers in other disciplines related to improving a design project. Designing is a vast and complex concept that requires years of practice and patience to encompass several social science disciplines.

Q13. Can you guess what should have been my profession?

A13.  My discipline is Industrial engineering with a major in Human Factors oriented toward designing interfaces for products and systems. Consequently, my major required taking multidisciplinary courses in marketing, psychology and econometrics and mostly targeting various methodologies for designing experiments, collecting data and statistically analyzing gathered data in order to predict system’s behavior.





January 2021

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