Introduction To Systems Engineering CSC 595_495 Spring 2018 Professor Rosenthal Midterm Exam Answer Key

Transcription

1 Part 1. Each question is worth 4 points. 1. Define what a system is. Introduction To Systems Engineering CSC 595_495 Spring 2018 Professor Rosenthal Midterm Exam Answer Key A system is a construct or collection of different elements that together produce results not obtainable by the elements alone. The elements, or parts, can include people, hardware, software, facilities, policies, and documents; that is, all things required to produce systems-level results. The results include system level qualities, properties, characteristics, functions, behavior and performance. The value added by the system as a whole, beyond that contributed independently by the parts, is primarily created by the relationship among the parts; that is, how they are interconnected. 2. List any four of the eight primary life cycles functions of a system? Development Verification Manufacture Training Deployment Operation Support Disposal 3. List four systems engineering activities. Requirements analysis, validation and verification Functional analysis and allocations Performance and reliability analysis and trade studies System architecture specification Life-cycle cost analysis including cost of quality 4. List four characteristics of a good systems engineer. Understands the fundamentals of mathematics, physics, and other pertinent sciences, as well as the capabilities of various people and disciplines Has mastered a technical discipline and learned multiple disciplines Must understand the end game and overall objectives of the endeavor 1

2 Creates a vision and approach for attaining the objectives May be an architect or designer Selects and shapes the technical issues to be addressed by multidisciplinary teams Must often interpret and communicate objectives, requirements, system Architecture, and design Is responsible for the design s technical integrity Organizes and leads multidisciplinary teams Is responsible for the successful delivery of a complex product or service 5. Define traditional top-down engineering. Top down approach starts with the big picture. It breaks down from there into smaller segments. A top-down approach (also known as stepwise design and in some cases used as a synonym of decomposition) is essentially the breaking down of a system to gain insight into its compositional sub-systems in a reverse engineering fashion. In a top-down approach an overview of the system is formulated, specifying, but not detailing, any first-level subsystems. Each subsystem is then refined in yet greater detail, sometimes in many additional subsystem levels, until the entire specification is reduced to base elements. A top-down model is often specified with the assistance of "black boxes", which makes it easier to manipulate. 6. Why is the Vee model more representative of modern systems engineering? The Vee model takes into account how you will assemble, integrate, verify and validate the system while you are defining and designing it. 7. Define what a prototype is. A prototype is an early sample, model, or release of a product built to test a concept or process or to act as a thing to be replicated or learned from. 8. Define the term external interface. A set of entities that interact with the system via external physical and logical interfaces Physical The actual wires and signals that connect two systems together Logical The formats of the data, packets, etc. and the meaning of that data 9. What is meant by the system context? Give an example. The system context is he set of entities that can impact the system, but cannot be impacted by the system. For example, a navigation system may accept an input on a road closure, but cannot impact that road closure 2

3 10. List and describe the 5 architectural viewpoints. Concept of Operations (CONOPS) A document describing the characteristics of a proposed system from the viewpoint of an individual who will use that system. It is used to communicate the quantitative and qualitative system characteristics to all stakeholders. Functional (or Logical) Architecture Defines the system s functions and the data that flows between the functions Physical Architecture Identifies and partitions the resources required to perform the logical functions Allocated Architecture Maps from functions to resources Interface Architecture Describes both the internal and external interfaces 11. Write four good, well formed, performance and/or reliability requirements. The primary storage system shall provide up to 2 TB of storage. The WAN shall provide a service of no less than 100 megabits per second to a networked modem. The system shall present an answer to a search requiring up to 12 joins in the system database in no greater than 3.0 seconds. The spacecraft shall provide cabin ventilation equivalent to 4 cabin air exchanges per crewmember per hour while crew is present after an emergency landing. The system shall be available to the user providing the normal mode of performance (described elsewhere) % of the time. The mean time between system failure (MTBF) shall be no less than hours. The time used in calculations shall be accurate to 10-7 seconds. The rod shall be able to bend a minimum of 60 0 in each direction at Celsius a minimum of 4500 times. 12. What are the five things that an operational concept document must show? What Defines the components, modules, elements and requirements that are a part of the system (at a high level) Where Defines the components and interfaces (geographical, physical or functional) that accomplish each required function When Defines the event sequences (tasks, sequences flows) that are required to complete the mission goals Who Defines the various users of the system (human, other systems, etc.) Why Defines the reasoning for the decisions made. 3

4 13. What are the three types of system properties that we model? Entities, attributes and relationships are the properties. 14. List the four model categories. For each category list one subcategory. Model Categories Model Subcategories Physical Full-scale mock-up Subscale mock-up Breadboard Quantitative Analytic Simulation Judgmental Qualitative Symbolic Textual Graphic Mental Explanation Prediction Estimation 15. Define both syntax and semantics. Languages have a syntax its grammatical structure - and its semantics - which give it meaning Syntax is the study of the principles and rules for constructing sentences in natural languages. It describes the way words are grammatically put together to form statements or sentences Word order, parts of speech, types of sentences, etc. are studied in syntax. Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they represent Elements like ambiguity, the relationship between words and sentences based on meaning are studied in language 4

5 Part 2. Each problem is worth 20 points. 1. Draw a hierarchy of natural science and mathematics books in a library. The top box should read Natural Science and Mathematics books. There must be at least three boxes at level 2 and for at least one of those three boxes at level 3. At least one element should fan out through level 4 with at least three additional boxes. 5

6 2. Draw a simple A0 level IDEF diagram that shows the functions involved in homework from initial creation by the professor through the grade being transmitted to the student as output. There are functions for both the professor and the student at level A0. There should be from four to six functions. 3. Medical Office Use Cases Model Model the following. Patient enters and signs in, updating the Waiting Room Wait List. As part of the sign-in the user s eligibility is checked using the Check Eligibility use case. The Nurse reads the next name from the Wait List. The Nurse uses the Query Patient Record and Update Patient Record use cases to update the Patient Record. The Doctor uses the Query Patient Record and Update Patient Record use cases to update the Patient Record. Hint: The actors are: Patient Patient Record Wait List Nurse Doctor 6

7 The use cases are: Sign-in Check Eligibility Update Waiting Room Wait List Read Wait List Query Patient Record Update Patient Record 7