bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacokinetics and Pharmacodynamics of Labetalol in Elderly and Young Hypertensive Patients Following Single and Multiple Doses
Authors: Rocci Mario L. , Vlasses Peter H. , Cressman Michael D. , Sirgo Mark A. , Plachetka John R.
Published: September 2023

Several physiologic changes accompany the aging process and may alter the pharmacokinetics and pharmacodynamics of drugs given to elderly patients. The primary purpose of the present investigation was to compare the pharmacokinetics of labetalol in young and elderly hypertensive patients. Limited data regarding the pharmacodynamics of labetalol in each of these age groups were also evaluated. Ten young (age 32–48 yrs) and nine elderly (age 60–68 yrs) patients with essential hypertension were evaluated after the first and last doses of a 15‐day regimen of labetalol. The young group received 200 mg orally at 9:00 P.M. and 9:00 A.M.; the elderly group received 200 mg once daily at 9:00 P.M. No significant differences in the mean (SD) apparent oral clearance of the drug existed between groups after the first [4.8(1.9) and 4.3 (1.2) L/hr/kg] and final [4.4 (2.2) and 3.4(1.0) L/hr/kg] doses of labetalol. No changes in any pharmacokinetic values for labetalol were detected as a function of age. Changes in standing blood pressure and heart rate after the first and last doses were generally similar between the young and elderly hypertensives. Labetalol was effective and well tolerated in both groups.
NCAM Mediates Adhesion Between Gonocytes and Sertoli Cells in Cocultures from Testes of Neonatal Rats
Authors: ORTH JOANNE M. , JESTER WILLIAM F.
Published: September 2023

ABSTRACT:During neonatal development of the rat testis, gonocytes resume mitosis and display renewed motility to migrate toward the basal lamina, two events that occurin vitrowhen these cells are cocultured with Sertoli cells. However, although substantial evidence suggests that development of gonocytes depends on Sertoli cells, little is known of how these cell types interact beyond our previous observations that they communicate via gap junctions and adhere avidly to each other. In the present study, we utilized several approaches to examine the mechanism by which gonocytes adhere to Sertoli cellsin vitro. First, we characterized this attachment in general by (1) determining its susceptibility to brief trypsinization in decreasing concentrations of Ca2+, (2) assessing the ability of gonocytes to adhere to Sertoli cells at reduced temperature, and (3) examining the effect of phospholipase C treatment on the number of gonocytes attached to a Sertoli cell monolayer. Because the findings suggested that a non‐cadherin mechanism is involved, we used immunofluorescence to identify the presence of neural cell adhesion molecule (NCAM) at virtually all gonocyte‐Sertoli cell (and Sertoli cell‐Sertoli cell) boundaries and found that incubation of cocultures in the continuous presence of NCAM antibodies caused release of essentially all gonocytes (but not Sertoli cells) from the monolayer. We also found, in (3) above, that gonocyte‐Sertoli cell adhesion was very susceptible to phospholipase C in cocultures isolated from newborns and maintainedin vitrofor 2 hours or 1 day but not in cultures maintained for 3 days. Moreover, cells isolated from pups 5 days old were as resistant to enzyme treatment at 2 hours postplating as were cultures from newborns after 3 daysin vitro. Thus, the way in which gonocytes adhere to Sertoli cells appears to change during the immediate postnatal period, as reflected by the observed change in phospholipase sensitivity, perhaps indicating production of a phospholipase C‐resistant NCAM isoform by several days after birth. These data constitute new information on the way in which postnatal gonocytes adhere to Sertoli cells and provide a basis for future work in our ongoing exploration of germ cell development in the neonatal rat testis.
Deformation of the Rat Sertoli Cell by Oral Administration of Carbendazim (Methyl 2‐Benzimidazole Carbamate)
Authors: NAKAI MASAAKI , HESS REX A. , NETSU JUN , NASU TETSUO
Published: September 2023

ABSTRACT: Carbendazim (methyl 2‐benzimidazole carbamate; MBC) has been reported to disrupt the microtubules of Sertoli cells in the rat, suggesting that the cells exposed to carbendazim would fail to maintain their shape due to the loss of their cytosketeton. The present study was performed to determine whether exposure to carbendazim induced Sertoli cell deformation. For this purpose, changes in the shape and position of Sertoli cell nuclei, that appear to be associated with changes in the shape of the cells themselves, were observed in stage VI‐VII seminiferous tubules of rat testis at 3 hours following treatment. Light microscopy and computer‐aided three‐dimensional reconstruction were also performed to survey the outline of the body. In the controls, parallel‐positioned nuclei (nuclei with their longer axis parallel to the basement membrane), perpendicular‐positioned nuclei (nuclei with their longer axis perpendicular to the basement membrane), and round‐shaped nuclei (nuclei showing a round or regular triangular profile) accounted for approximately 52%, 35%, and 13% of the total, respectively. In Sertoli cells showing carbendazim‐induced sloughing of germ cells, however, parallel‐positioned nuclei accounted for 21% and the round‐shaped nuclei for 51% of the total. Approximately 69% of perpendicular‐positioned nuclei were located in the basal part of the cells in the controls, compared with 95% in tubules showing carbendazim‐induced sloughing. These changes in individual parameters were significantly different (α < 0.05). Light microscopy and computer‐aided reconstruction indicated that the body region of Sertoli cells in the control testis was columnar in shape, whereas that of Sertoli cells that showed sloughing was conical. These findings suggest that Sertoli cell cytoplasm, following carbendazim‐induced sloughing, moves toward the base of the cellular axis.
Characterization of Two Second Messenger Pathways and Their Interactions in Eliciting the Human Sperm Acrosome Reaction
Authors: Doherty Carolyn Maud , Tarchala Susan M. , Radwanska Ewa , de Jonge Christopher J.
Published: September 2023

ABSTRACT: The human sperm acrosome reaction (AR) occurs via the activation of at least two signal transduction pathways. The purpose of this investigation was to characterize two of the pathways, the protein kinase A (PKA) and C (PKC) pathways, and determine whether pathway “crosstalk” occurs between them in eliciting the AR in capacitated spermatozoa. Stimulators of each pathway were tested in a dose‐dependent manner. ARmax, EDM50, and δARmax (%ARmax — %ARcontrol) values were calculated. The PKA pathway stimulators forskoiin and dibutyryl cyclic AMP (dbcAMP) induced an ARmax at 1.0 μM and 1.0 mM, respectively. The EDW and δARmax values were: 0.01 μM and 17% for forskoiin and 0.069 mM and 13% for dbcAMP. Two stimulator types of the PKC pathway were tested: synthetic diacytglycerols (DG) and a phorbol diester. 1,2‐dioleoyl‐sn‐glycerol and 1,2‐dioctanoyl‐sn‐glycerol, analogues of the PKC‐activating second messenger DG, each induced an ARmax, at 50 μM. The ED50 and δAR max values were: 33 μM and 24% for 1,2‐dioleoyl and 34.8 μM and 34% for 1,2‐dioctanoyl. 4β‐Phorbol‐12, 13‐didecanoate, a PKC stimulator, induced an ARmax at 0.1 μM. The ED50, and δARmax were 0.021 μM and 26%. An inhibitor of each kinase was added at the end of the capadtation period and prior to stimulation by inducers at their ARmax dose. KT5720, a PKA inhibitor, caused a dose‐dependent reduction of the forskolin and dbcAMP‐induced AR. Calphostin C, a PKC Inhibitor, prevented stimulation of the AR by 1,2‐dioleoyl and 4β‐phorbol‐12, 13‐didecanoate. To investigate pathway “crosstalk,” the following experiments were conducted: (1) stimulators of each pathway were combined and tested at the ARmax and ED50 concentrations for each; (2) spermatozoa were pretreated with a kinase inhibitor and then stimulated using an alternative pathway stimulator; and (3) a PKA or PKC inhibitor and a combination of PKA and PKC stimulators, at ED50 concentrations, were tested. The results for (1) indicate an additive AR response for ED50 concentrations but not for ARmax doses. The results for (2) demonstrate that a kinase inhibitor for one pathway prevents induction of the AR by a stimulator of the alternative pathway. Finally, the results for (3) show that a kinase inhibitor for one pathway prevents induction of the AR by the combined use of separate pathway stimulators. When taken collectively, the present results suggest a convergent mechanism of crosstalk between the PKA and PKC pathways leading to the human sperm AR.
Altered Basement Membrane Synthesis in the Testis After Tissue Injury
Authors: RICHARDSON LAURA L. , KLEINMAN HYNDA K. , DYM MARTIN
Published: September 2023

ABSTRACT: The basement membrane plays an important role in maintaining the structural and functional integrity of tissues. Altered basement membrane structure has been associated with severe functional impairment of the testis in several conditions, including vasectomy, autoimmune orchitis, cryptorchidism, and following x‐irradiation. We have used efferent duct ligation as a model to examine seminiferous tubular basement membrane morphology, synthesis, and gene expression to determine whether altered basement membrane synthesis is responsible for the aberrant structures noted after tissue injury. On days 2 and 3 after ligation, both the seminiferous epithelium and the basement membrane appeared normal, but 7 days after ligation, the seminiferous epithelium began to degenerate. The basement membrane appeared detached from the epithelium, and redundant patches of basement membrane were observed adjacent to the Sertoli cells at 14 and 21 days postligation. Immunoprecipitation indicated an increase in laminin protein synthesis in the ligated tubules at the same time. Northern blot analysis showed increases in transcript levels for laminin as well as collagen IV and heparan sulfate proteoglycan. These data show that new protein synthesis is responsible, at least in part, for the duplication of the basement membrane coincident with the tissue damage caused by efferent duct ligation.
Cloning and Characterization of an Androgen‐Dependent Acidic Epididymal Glycoprotein/CRISPI‐like Protein From the Monkey
Authors: SIVASHANMUGAM PERUMAL , RICHARDSON RICHARD T. , HALL SUSAN , HAMIL KATHERINE G. , FRENCH FRANK S. , O'RAND MICHAEL G.
Published: September 2023

ABSTRACT: A cDNA encoding an acidic epididymal glycoprotein (AEG)‐like, CRISP1 (cysteinerich secretory protein) protein from the monkey (Macaca mullata) epididymis has been cloned and sequenced. The monkey AEG (mAEG) has an open reading frame that encodes a protein containing 249 amino acids with a deduced molecular mass of 28 kDa. The mAEG protein sequence is 85% identical to human and 44% identical to mouse CRISP1, including all 16 conserved cysteine residues. mAEG also shows a significant amino acid homology with other CRISP proteins, rat AEG/DE, human TPX1/CRISP2, and guinea pig acrosomal autoantigen 1 (AA1). In addition, mAEG shows somewhat less homology to a toxin from the Mexican beaded lizard and to a human glioma pathogenesis‐related protein. Northern blot analysis shows that the mRNA for mAEG is expressed in all the regions of the epididymis except the caput and was not detected in the testis, prostate, seminal vesicle, and brain. In castrated animals, mAEG gene expression in the epididymis is significantly diminished; however, testosterone enanthate replacement restored the normal level of expression, demonstrating that expression of mAEG is androgen dependent. Western blot analysis of monkey epididymal regions using mouse antirecombinant human AEG identified a 28‐kDa protein only in the caudal region. Immunohistochemical analysis identified mAEG only in the principal cells of the cauda epididymal epithelium. Immunofluorescence analysis identified mAEG on the principal piece of the sperm tail and as small patches over the middle piece and head regions. The results described in the present study suggest that mAEG (CRISP1) is secreted in the monkey epididymis, regulated by androgens and present on epididymal spermatozoa.
A Lower Dosage Levonorgestrel and Testosterone Combination Effectively Suppresses Spermatogenesis and Circulating Gonadotropin Levels with Fewer Metabolic Effects Than Higher Dosage Combinations
Authors: ANAWALT BRADLEY D. , BEBB RICHARD A. , BREMNER WILLIAM J. , MATSUMOTO ALVIN M.
Published: September 2023

ABSTRACT: Studies using exogenous high‐dosage testosterone (T) or a combination regimen of physiologic T plus high‐dosage levonorgestrel (LNG) administration in normal men have shown that oligoazoospermia (<3 million/mL) or azoospermia can be achieved in the majority of the men. However, these hormonal regimens have been associated with significant weight gain and suppression of serum high‐density lipoprotein (HDL) cholesterol levels. We hypothesized that a combination of physiologic exogenous testosterone and lower dosage LNG would result in uniform severe oligoazoospermia or azoospermia in normal men but would cause fewer adverse metabolic side effects. We conducted a randomized, placebo‐controlled, single‐blind trial comparing 6 months of T enanthate (100 mg IM, weekly) plus LNG, 125 μg by mouth, daily (LNG 125; n = 18) or LNG, 250 μg by mouth, daily (LNG 250; n = 18) and compared these regimens with our previous study of the same dosage of T enanthate combined with placebo LNG (LNG 0; n = 18) or with 520 mg of LNG (LNG= 520; n = 18). All three combination regimens of T enanthate and LNG suppressed spermatogenesis more rapidly and resulted in significantly more uniform severe oligoazoospermia (<1 million/mL) than the T‐alone regimen. Severe oligoazoospermia was achieved in 89% of the LNG 125, 89% of the LNG 250, and 78% of the LNG 520 groups, respectively, versus 56% of the men in LNG 0 (P < 0.05 for the combination groups vs. LNG 0), but there were no significant differences between the combination regimens (P = NS). All four groups gained significant weight compared with their baselines, although the gain tended to be greater as the dosage of LNG increased (2.0 ± 0.9, 2.9 ± 1.1, 3.6 ± 1.0, and 5.4 ± 1.0 kg gained, compared with baseline in the LNG 0,125,250, and 520 groups respectively; P < 0.05 compared with baseline). Serum levels of HDL cholesterol decreased in all of the groups, but the effect was larger as the dosage of LNG increased (4 ± 4% vs. 13 ± 4%, 20 ± 3%, and 22 ± 4% decrease in HDL levels from baseline in the LNG 0, LNG 125, LNG 250, and LNG 520 groups respectively; P = 0.06 for LNG 125 compared with LNG 0, and P < 0.05 for LNG 250 and LNG 520 compared with LNG 0). We conclude that 1) the combination of physiologic exogenous T enanthate and LNG suppresses spermatogenesis more effectively than T enanthate alone and that 2) the combination regimen of T enanthate plus lower dosage LNG suppresses sperm production comparably to T enanthate plus higher dosage LNG, while causing less weight gain and HDL cholesterol suppression. A combination regimen of physiologic testosterone plus a low dosage of levonorgestrel offers great promise as a safe and effective male contraceptive regimen.
Evidence That in a Physiological Setting Sertoli Cell Number Is the Major Determinant of Circulating Concentrations of Inhibin B in the Adult Male Rhesus Monkey (Macaca mulatto)
Authors: RAMASWAMY SURESH , MARSHALL GARY R. , McNEILLY ALAN S. , PLANT TONY M.
Published: September 2023

ABSTRACT: The relationship between changes in Sertoli cell number and function and changes in circulating inhibin B concentrations was investigated following unilateral orchidectomy (UO) in the adult rhesus monkey. As expected, the 50% loss in Sertoli cells resulting from UO on day 0 was associated with a rapid and corresponding decline in plasma concentrations of inhibin B. The decrease in inhibin B levels was sustained until the remaining testis was removed on day 44, at which time a compensatory 50% increase (P < 0.05) in the number of round spermatids was evident in the absence of a change in Sertoli cell number. Moreover, Sertoli cell number and inhibin B levels among individual monkeys were highly correlated (r2= 0.65, P < 0.202). Round spermatid number and inhibin B, however, were poorly correlated (r2= 0.37, P < 0.04). These findings indicate that, in a physiological setting where the negative feedback control system governing the adult primate testis is operational, Sertoli cell number, rather than function, is the primary determinant of circulating inhibin B levels.
The Systems Engineering Process Working Group: A Status Report
Authors: Wray Richard B.
Published: September 2023

The national body of the National Council on Systems Engineering (NCOSE) has chartered the Systems Engineering Process Working Group (SEP WG) to refine and describe systems engineering processes). The challenges and questions have been identified, goals and results needed have been defined, and a development approach selected. Active since April 1992, the SEP WG has made progress in resolving some key issues and preparing a description which is useful to the practicing systems engineer. This paper describes the background, action plan, approach and current status of the SEP WG.
STATE OF THE PRACTICE‐COMMERCIAL SYSTEMS ENGINEERING
Authors: Iliff Randall C.
Published: September 2023

This paper was prepared to document the current state of Systems Engineering practice in the Commercial Sector. The paper covers Commercial Sector acceptance / application of Systems Engineering and related National Council on Systems Engineering (NCOSE) activities to date. Underlying factors motivating recent changes to the role of Systems Engineering in the Commercial Sector are also identified and discussed.
ADAPTIVE SYSTEMS ENGINEERING: A CONCEPTUAL MODEL
Authors: Shenhar Aaron J. , Bonen Zeev
Published: September 2023

The conceptual and theoretical basis of systems engineering and project management are still in their early days. For example, almost all literature written in recent years in these areas tend to assume that all projects are fundamentally similar and their management consists of a universal set of functions and activities. Systems engineering books usually describe a system's lifecycle (phases) and typical systems engineering process activities along these phases. In practice however, there are salient differences among systems according to size, industry, customer type, contractor's organization, level of technology and other parameters.

Based on an exploratory, on‐going field study we suggest in this paper a conceptual, two dimensional framework for the classification of projects and systems and show how this framework can be used to distinguish among systems engineering styles and practices for various types of engineering projects. Projects are classified according to their level of technological uncertainty at the moment of project initiation and their system scope which is their location on a hierarchy of systems and subsystems. The technological uncertainty dimension is divided into: low‐tech, medium‐tech, high‐tech, and, super high‐tech projects. System scope is divided into: assembly, system and array projects. Considerable differences were found among systems engineering methods along each one of the model's axes. Differences were also observed for a simultaneous change in both dimensions.
REAL TIME SYSTEMS/SOFTWARE METHODOLOGIES FOR LARGE AEROSPACE SYSTEMS
Authors: Patel Bhadra K. , Tamanaha Doris Y. , Rudzik Laurel A.
Published: September 2023

This paper presents an overview of the real time system/software methodology approach being deployed within Hughes Aircraft Company. The Hatley‐Pirbhai Process for System Development (PSD) was chosen as the training standard for all systems and software engineers in a common engineering method to increase productivity, quality of design, and communications between various engineering disciplines. The approach that Hughes has taken is to adopt a well defined and proven methodology available from industry and to customize it to include specific extensions applicable to the types of systems developed by Hughes Aircraft product organizations. Two such extensions, information modeling and requirements traceability tooling, are discussed in this paper. In conclusion, the paper will discuss the lessons learned for using the integrated system development methodology and follow‐on activities that are being worked on today.
Functional Analysis Vs. Object Oriented Analysis, A View from the Trenches
Authors: Brown Phillip J. , Cady Kim A.
Published: September 2023

System engineering has long used a structured analysis approach widely known as functional analysis. Recent experience in software development has resulted in a growing enthusiasm for object oriented analysis, a system analysis technique focused on the objects within the system, and the objects external to the system, with which the system interacts. While many analysts view these two perspectives as an either/or choice, this paper contends that these methods are complementary, providing system and software engineers a cross‐checking process for establishing a stable set of well defined requirements. Furthermore, exploitation of the unique strengths of each approach yields a diminishing volume of work as the software sub‐elements are refined for use in a production system.
ACCELERATING SYSTEM INTEGRATION
Authors: Jenkins Roger , VanNostrand Erik
Published: September 2023

This paper presents a case study on the combined contributions of system simulation, technical interchange, and innovative methods of system analysis toward the acceleration of system integration. The combination of these three efforts cut cost and increased productivity so that aggressive program schedules could be maintained. Capitalizing on unique opportunities, simulations and innovative real time methods of analysis played a key role in the timely integration of a highly advanced multiprocessor system.
“Working Together”: The Boeing 777 Cabin Management System
Authors: Morrison Arthur F.
Published: September 2023

The new Boeing 777 Cabin Management System (CMS) is being developed by the Boeing Defense & Space Group Commercial Avionics Systems (CAS) for the Boeing Commercial Airplane Group (BCAG). CAS is performing the detailed system engineering based on BCAG provided system requirements. With both of these groups involved in the development effort, the system engineering process being employed utilizes system engineering elements from both organizations. As might be expected, combining system engineering methods from both groups necessitates the use of an integrated approach. Challenges arise from administrative as well as technical viewpoints. Many considerations have to be addressed, including the level of functional development and system architecture definition specified by each group, the use of requirement development teams and their responsibilities, the form and content of the deliverable system engineering products, and the establishment of and requirements for key system engineering milestones.

This paper defines the various aspects of the system engineering approach being applied to the Boeing 777 CMS system engineering task. The steps that have been taken to integrate the two groups are explained and analyzed to provide insight into how to apply an integrated system engineering approach to a product development effort.
Automated Optimization of Systems Architectures for Performance
Authors: Oliver David W.
Published: September 2023

This paper provides a brief executive level description of Model Based Systems Engineering, (MBSE). It introduces the seven abstract core engineering steps that can be used to describe the engineering process and make the process tailorable. A representative set of tools is described that can span the engineering work.

The MBSE process, with a tool set is described, as a means to automate the search of the application solution space for feasible or near optimal systems solutions. The approach applies to distributed and real‐time systems. A by‐product of the approach is an automated ability to reuse systems specifications and systems designs.

A simple example is provided to show how the optimization works. It shows how modeling and automation augment inspired engineering but do not substitute for it. Substantial work is needed in information standards for systems, tools integration, and search procedures.
Educating System Engineers: What Industry Needs and Expects Universities or Training Programs to Teach
Authors: Might Robert J. , Foster Robert A.
Published: September 2023

Do universities provide industry with System Engineers (SEs) that industry expects and wants? Are company sponsored training programs for System Engineers a worthwhile investment? Unlike traditional engineering disciplines, there is no prescribed educational program for Systems Engineering that meets the majority of industry's needs. Consequently, there appears to be no way for an organization to hire graduates who will, with certainty, be qualified to perform the majority of systems engineering functions within that organization. How much of this is due to the lack of standardization within industry, and how much is due to the lack of a standardized academic curriculum? This paper presents results of an empirical study aimed at identifying answers to these and other questions that are extremely important to the development of a close, effective partnership between industry (the customer) and educational/training programs (the producers).
THE NASA/USRA UNIVERSITY ADVANCED DESIGN PROGRAM: A SYSTEMS ENGINEERING EXPERIENCE
Authors: Johnson Vicki S. , Rumbaugh Barbara A.
Published: September 2023

This paper describes the NASA/USRA University Advanced Design Program (ADP) and the role it plays in providing a systems engineering experience for senior engineering students in “capstone” design courses. Experience with the program has resulted in conclusions about the factors that contribute to a positive experience in the course, with parallels drawn to the “real world.” The paper also presents on‐going ADP activities designed to expand the impact of the program to a wider community.
Database Generated Software Requirements Specification
Authors: Crocker Don
Published: September 2023

The goal of software requirements management at Grumman is to provide Systems Engineering's internal and external customers with the right information to produce and evaluate a computer program that meets the system's needs. A valuable approach to requirements management is to model one or more aspects of a system and communicate and control the system and software requirements via a database of the model elements.

Engineering models can range from abstract models such as a series of partial differential equations for the solution of harmonic vibrations to isomorphic models such as a data flow diagrams or perspective drawings. The modeling method chosen uses a graphical notation and an Entity‐Relationship‐Attribute (ERA) database to create four isomorphic models to define a system and is currently implemented using RDD‐100® from Ascent Logic Corporation.

The models used to specify the system are:

1) Design Knowledge Capture (DKC) model‐an ERA model of the requirements flowdown from the perceived need to the requirements specification. 2) Behavior model – built using entities that represent functions and items, along with temporal notations of the functional flow. 3) Physical model –sometimes called the system architecture, includes the hierarchical structure of the components that build the system, the interfaces between the components, and the physical links that comprise the interfaces. 4) Resource model‐allows the engineer to evaluate the amount of resources needed when specified behavior is exhibited by a system architecture and to determine the behavior of the system when resources are depleted.

The customization of the RDD language and the augmentation of RDD with other tools to add the required capability is described. The elements of the model are mapped from the RDD database to the an expansive interpretation of the Data Item Description for a Software Requirements Specification (DI‐MCCR‐80025A). The interpretation is based on interchanges between the requirements provider and the requirements implementor.

The paper describes the aspects of systems specified using the database of models method. The method is heavily driven by the need to meet the MIL‐STD 2167A requirements for a Software Requirements Specification. However; the main value of this paper may be in the identification of the information produced while engineering the system that is not in the Systems Requirements Specification (SRS).
IN DEFENSE OF THE TRADITIONAL SYSTEM REQUIREMENTS ANALYSIS PROCESS
Authors: Grady Jeffrey O.
Published: September 2023

Some new requirements tools and techniques carry with them the suggestion that the traditional system requirements analysis (SRA) process is somehow deficient and passé. This paper re‐visits that process, expands its structured decomposition techniques to include alternatives to functional flow diagramming, augments it with structured interface, environmental, and specialty engineering requirements analysis and adapts it to the Integrated Product Development (IPD) approach.

In the traditional SRA approach, it was never clearly explained how it began, leaving many to conclude that there was a chicken‐and‐egg problem hiding in there somewhere. It also was never clear where it ended (decompose as required). Some have concluded that the process has neither beginning nor end, only a very expensive middle producing paper of great mass but questionable utility. The traditional process also focused principally on performance requirements. It provided an effective demand driver for only one of three kinds of constraints and had little to offer for programmatic requirements analysis.

All of these shortcomings are disposed of in this paper revealing a comprehensive, flexible, and robust approach to project‐wide requirements analysis linked to recent advances like quality function deployment (QFD), IPD concepts, and the U.S. Air Force integrated planning initiative. The process is described more fully in a new book about an old process titled System Requirements Analysis (Grady 1993).
SYSTEMS ENGINEERING PERFORMANCE ANALYSIS THROUGHOUT THE SYSTEMS ACQUISITION LIFECYCLE
Authors: Atallah George C.
Published: September 2023

Today's systems and their applications incorporate a variety of complex, physical, logical, and human elements. The interactions between these elements are often so complex that intuition alone is not sufficient for estimating the performance indices of interest. These systems, under a tremendous heavy workload, are expected to generate high throughput at a reasonable level of resources' utilization, fast response time, and maintain high level of quality (such as availability, reliability, and maintainability). These challenging technical performance specifications have imposed on the applications of interest numerous critical technical problems throughout their entire acquisition lifecycles. This paper defines, introduces and addresses a comprehensive systematic performance process to quantify and analyze these technical problems. This performance process identifies and organizes the system performance measurements; structures and addresses its major steps throughout the entire system acquisition lifecycle. Proper implementation of this performance process will ensure on time delivery of high quality and low cost systems.
Application of Continuous Improvement Methods to Systems Engineering Tasks: A Case Study
Authors: Davis Juliet G.
Published: September 2023

Continuous Process Improvement as an organizational culture is recognized in the 1990's as a key to success in a competitive industry. Application of formal Continuous Improvement methodology on long established tasks presents significant challenges for both staff and management at Rockwell International Space Systems Division. This paper shares the experiences of one Systems Engineering project function in its attempt to incorporate structured Ci practices into the performance of contract tasks. Process decomposition, development and use of product metrics, and the implementation of improvements within various processes are described. Successes, failures, and lessons learned from the experiences are summarized as a guide for future endeavors.
EXECUTABLE MODEL SUPPORT FOR RISK MANAGEMENT
Authors: Alford Mack
Published: September 2023

This paper presents a method to augment the traditional Work Breakdown Structure model, used for management planning, to yield an executable model that incorporates risk management concepts. Methods for using this model to help the manager understand the cost and schedule implications of project uncertainties and other project risks are discussed.
RISK ASSESSMENT AND MITIGATION PLANNING EARLY IN THE DEVELOPMENT LIFE CYCLE
Authors: Booth Stuart
Published: September 2023

This paper presents a risk management process and how it will serve as a basis for test and analysis planning early in the development life cycle. To strengthen this process, integrated databases are available to provide mapping between the system design data and the derived risk metrics that test engineers can use to develop their test and analysis plans. As the development life cycle progresses and matures, the original risk forecasting can be updated providing a real‐time assessment of the design.
Can MIL‐STD‐499B Be Adapted for Resource Management and Saving the Environment?
Authors: Martin Frederick , Daetz Douglas
Published: September 2023

Management of resources and the environment is increasingly prominent in the national and global debates on policy. In the U.S. resources and the environment involve a broad range of national policy issues with complex tradeoffs: forest management to maximize yield and maintain biodiversity; alternative fuels for power plants that must meet the requirements for environmental protection, pollution control, performance and community acceptance; allocation of water, a resource in short supply in the southwest. At the local government level, there are local issues such as: locating a new municipal golf course in a county boasting a unique combination of natural environment, agriculture, sophisticated suburban population and a thriving commerce; designing and implementing local welfare assistance programs in a climate of opposition to new taxes. On a global scale, the World Bank announced that all future projects funded by it will be fully examined for their impact on the environment.

In the political arena almost none of these issues are heading towards a rational solution, and for most of them there is only a vague definition of the problem.

These issues are a system engineer's nightmare (or challenge)! Why? Unlike the traditional Department of Defense programs with well specified systems, the issues of resources and the environment touch many subsystems in a large, multivariable environment. Many of the variables, e.g., those associated with the weather, national economy, business climate, and international political situation are largely or completely beyond the control or influence of the planners, architects, and engineers. The professional must carry out the task of building a successful project in an environment of extreme uncertainty and limited control.

In this paper we examine the features of MIL‐STD‐499B to see how they could be applied to managing resources and the environment for a project that is a subsystem embedded in a very uncertain environment. We shall look at the process of identifying the problem to be solved and establishing the interfaces of the subsystem to the larger world systems. We also consider how to deal with the life‐cycle issues. For example, can one define the life‐cycle process for a golf course?

Finally, we shall pose the following dilemma. Resource management as practiced by the former Soviet Union and its satellites has proven to be a failure. Is system engineering for resource and environmental management a paradox or a panacea in a democratic, free‐market society?
A CONCURRENT GOVERNMENT/CONTRACTOR APPROACH FOR DEVELOPING DESIGN CONSTRAINTS
Authors: Shimizu Choichi , Goerke Leah
Published: September 2023

Specifications which define the requirements of a system, sub system, or end items consist of both performance requirements and design constraints. Performance requirements state what a system or item must do and how well it must do it. Design constraints state boundary conditions within which the system or item must perform (i.e., environments, reliability, physical characteristics). Design constraints typically form approximately 80% of the requirements in a specification.

Early definition and proper allocation of both the performance requirements and design constraints are essential to the successful development of the end item. At the Ballistic Missile Organization, the System Requirements Analysis (SRA) process has been used to synthesize system design and develop specifications from design constraints and performance requirements. This paper concentrates on the SRA process peculiar to design constraints. A team approach was used with both government and contractor technical experts. The entire process will be discussed from the initial identification of design constraints to the incorporation of these constraints into the specifications as authenticated requirements. This process is consistent with the latest system engineering standards being implemented.
THE THREE‐STEP PROCESS FOR MILESTONE AND REVIEW MANAGEMENT
Authors: Posner Stacy A.
Published: September 2023

The prevailing competitive environment has forced most companies to monitor their resources more stringently than ever before to ensure their optimal use. Consequently, program checkpoints and major milestones have gained greater attention from project managers, as well as corporate managers. This paper details the process activities necessary to successfully meet and pass through these milestones. Even though this process was developed specifically for MIL‐STD type reviews, the three‐step approach, P‐E‐P (Pre‐Event, Event, Post‐Event), can be implemented for any milestone or, in general, for any meeting.

Currently, Systems Engineering Management is evolving from a calendar‐driven process to an event‐driven process. The prime benefit of this three‐step approach embraces this trend by ensuring steady forward progress of a project/program regardless of size or the number of milestones. It also ensures that all work being done supports the project's mission and is directly traceable to its requirements and objectives. The three‐step process will identify inconsistencies, mistakes, or ambiguities as early as possible. Early error identification is paramount to reducing cost, since errors are more costly to correct the later they are discovered in the product life cycle. Thus, following this three‐step process allows for better response to change, ensures steady progress toward each milestone and minimizes overall cost through disciplined and structured planning and execution.
THE NEED FOR AUTOMATED VERIFICATION TOOLS FOR THE SYSTEMS ENGINEER
Authors: Swift Douglas Keith
Published: September 2023

Requirements Verification is an important aspect of Systems Engineering that suffers from a lack of practical tools specifically tailored to encompass the entire verification process. The need for automation is great, specifically for tools able to interface with relational databases. Most of the current Systems Engineering tool development is geared towards program synthesis and design, with less attention given to integration and verification. This paper examines the needs of Verification Engineers with emphasis on developing a computer based tool for automating and managing the verification process. A typical verification flow is outlined, the goals and benefits that could be derived from automation are reviewed, and then a hypothetical Verification Engineering Management System (VEMS) is described.
ORGANIZATIONAL CHALLENGES IN INTEGRATED PRODUCT TEAM IMPLEMENTATION
Authors: Cox James D.
Published: September 2023

This paper presents a brief case study of the obstacles encountered and lessons learned as a result of the implementation of the concurrent engineering process during the Engineering and Manufacturing Development (EMD) phase of the F‐22 program. The process is on‐going; the organizational structure and implementation procedures continue to evolve as the program matures. Results to date have been highly encouraging. Lockheed Aeronautical Systems Company is developing plans to implement the process on all of its existing and future defense programs.
Distributed Design of Computer Based Systems: Methodology
Authors: Oliver David W.
Published: September 2023

The distributed design of computer based systems requires a methodology that supports both the modeling of the distributed system and the ability to assess the impact of requirements and engineering change while the system is at any stage of development. Model Based Systems Engineering, MBSE, provides an approach to these twined problems with the advantages of tailorability to application, culture, notations, and tools. It is critical that traceability linkages be constructed in the normal course of engineering development and that they be adequate for an analysis of the impact of change.
TOWARD A USEFUL BEST COMMERCIAL PRACTICE
Authors: Weaver Charles L.
Published: September 2023

This paper presents the sequence of events and activities which have occurred as a major defense contractor began the migration to the commercial marketplace. This changeover has been focused on the need to modify development processes to continue to use the best parts of the discipline imposed by Military Standards (MIL‐STDs), yet streamline them to avoid cumbersome and unnecessary tasks. While the challenge to define an easy to use Best Commercial Practice has been more difficult and time consuming than originally anticipated, the results to date have been encouraging.
SE APPLICATIONS IN TRANSPORTATION PLANNING
Authors: Dolton Theodore A. , Hoy John P. , Cutler William H.
Published: September 2023

Systems engineering processes are designed to address the functions, elements and issues found in many complex systems, including those outside traditional aerospace industry programs. In this paper these processes are applied to transportation planning for a region ‐ the San Francisco Bay Area.

This paper examines the application of the Systems Engineering process, as established in the MIL‐STD‐499B, to this civil system. It considers the unique problems and differences such a civil system imposes on the 499B process. These are seen to be identifying the diffuse customer, which includes the various government agencies involved in the system as well as the public; identifying the requirements and functions of such a complex existing system; characterizing this system; and establishing ways to incorporate new technologies. Representative requirements and functional analysis are presented.
WHY SYSTEMS FAIL (VIEWED FROM HINDSIGHT)
Authors: Talbott Marvin
Published: September 2023

A two year study of several hundred reports analyzing system failures across diverse disciplines has identified seven reoccurring themes. The results are summarized, discussing the common contributory factors identified, and then each principle is illustrated with several diverse system failure occurrences.
MISCONCEPTIONS CONCERNING THE VALUE OF SYSTEMS ENGINEERS
Authors: Swift Douglas Keith
Published: September 2023

In the community of professional engineers, the Systems Engineer is often perceived as an inferior engineer. Misconceptions are especially prevalent among technical design engineers for whom up‐front Systems Engineering should be considered absolutely essential. The Systems Engineer often works in an environment where his engineering peers, and sometimes even management, considers his contribution to be subordinate, of second‐class value, and at times, a nuisance. This paper examines this critical problem from the perspective of an aerospace engineer who spent five years working as a flight controls design engineer (where Systems Engineering was treated with considerable bias), and men transferred into Systems Engineering and has since been working on the opposite side of the fence. An exploration into the causes of the phenomena is detailed in the paper, with special emphasis on the factors perpetuating these misconceptions. A set of practical recommendations (some applicable for working Systems Engineers and some applicable for Managers) is then presented for use in mitigating and eventually dissolving these non‐productive barriers.
Systems Engineering at the SSCL, A Case Study
Authors: Matz John E.
Published: September 2023

Systems Engineering (SE) as “defined” by DoD and NCOSE is compared to SE as “redefined” by the SSCL. How and why they differ are discussed. How a practical and pragmatic Systems Engineering program is organized and implemented is outlined with the rationale for the approach chosen. The progress to date, and the anticipated future of Systems Engineering at the SSCL is described.
5.1.1 Modular Vehicle Architectures: A Systems Approach
Authors: Rushton Gary J. , Zakarian Armen
Published: September 2023

Modular systems provide the ability to achieve product variety through the combination and standardization of components. In this paper, a methodology that combines the Hatley/Pirbhai system model, integration analysis, and optimization techniques for development of modular electrical/ electronic vehicle systems is presented. The approach optimizes integration and interactions of the electrical/ electronic system elements and creates functional and physical modules for the vehicle. The paper illustrates importance of system modeling in developement of modular products. Discussion on how to make the system modeling more attractive to the industry is also presented.
5.1.2 Chances for Systems Engineering in Road Transport and Traffic Telematics
Authors: Hadderingh J. N.
Published: September 2023

This paper highlights some of the possibilities for applying Systems Engineering in the field of Road Transport and Traffic Telematics (RTTT). Although large and often complicated systems are or will be applied in this field, they are often specified, developed, designed and commissioned without employing Systems Engineering (SE). This has resulted in long and cumbersome procurement processes and sub‐optimal solutions. Even more severe problems may occur with the need for further integration of these often stand alone systems. Applying SE may be a way to solve some of these problems. But it will require the use of this methodology in a field that is not (yet?) ready for it. This paper gives examples of some RTTT systems, shows what SE could do for them and gives a few suggestions for achieving these benefits.
5.1.3 Traceability in A Unified Systems Engineering Framework for A High‐Speed Railway System
Authors: Park Young Won , Song Hae Sang , Chung Heung Chae
Published: September 2023

This paper presents results from a computer‐aided systems engineering application to a high‐speed railway system technology development project, called KHST(Korea High Speed Train). RDD‐100 version of ALC Inc. was used in this work. The framework adopted in the study takes a unified approach to the system design and the process management associated with it, thereby coherent and full traceability between them is maintained. Conventional system engineering process supported by the tool is adopted in the KHST system design; however, some modification is inevitable because of a late introduction of the tool on the project. On the other hand, the same tool is also used to the systems engineering management to get full traceability between system design data and engineering management data. It is greatly helpful in managing many sub‐contractors in the sense that the traceability can help identify the sub‐project responsibility as well as the objectives of the project in coordination with interface requirements. We conclude with the advantage and limits of our unified approach.