Secondary Subsystem Research Articles

Environmental life-cycle comparisons of two polychlorinated biphenyl remediation technologies: Incineration and base catalyzed decomposition

Remediation action is critical for the management of polychlorinated biphenyl (PCB) contaminated sites. Dozens of remediation technologies developed internationally could be divided in two general categories incineration and non-incineration. In this paper, life cycle assessment (LCA) was carried out to study the environmental impacts of these two kinds of remediation technologies in selected PCB contaminated sites, where Infrared High Temperature Incineration (IHTI) and Base Catalyzed Decomposition (BCD) were selected as representatives of incineration and non-incineration. A combined midpoint/damage approach was adopted by using SimaPro 7.2 and IMPACTA2002+ to assess the human toxicity, ecotoxicity, climate change impact, and resource consumption from the five subsystems of IHTI and BCD technologies, respectively. It was found that the major environmental impacts through the whole lifecycle arose from energy consumption in both IHTI and BCD processes. For IHTI, primary and secondary combustion subsystem contributes more than 50% of midpoint impacts concerning with carcinogens, respiratory inorganics, respiratory organics, terrestrial ecotoxity, terrestrial acidification/eutrophication and global warming. In BCD process, the rotary kiln reactor subsystem presents the highest contribution to almost all the midpoint impacts including global warming, non-renewable energy, non-carcinogens, terrestrial ecotoxity and respiratory inorganics. In the view of midpoint impacts, the characterization values for global warming from IHTI and BCD were about 432.35 and 38.5 kg CO 2-eq per ton PCB-containing soils, respectively. LCA results showed that the single score of BCD environmental impact was 1468.97 Pt while IHTI's score is 2785.15 Pt, which indicates BCD potentially has a lower environmental impact than IHTI technology in the PCB contaminated soil remediation process.

Quantitative Assessment of Electrostatic Embedding in Density Functional Theory Calculations of Biomolecular Systems.

We evaluate the accuracy of density functional theory quantum calculations of biomolecular subsystems using a simple electrostatic embedding scheme. Our scheme is based on dividing the system of interest into a primary and secondary subsystem. A finite difference discretization of the Kohn-Sham equations is used for the primary subsystem, while its electrostatic environment is modeled with a simple one-electron potential. Force-field atomic partial charges are used to generate smeared Gaussian charge densities and to model the secondary subsystem. We illustrate the utility of this approach with calculations of truncated dipeptide chains. We analyze quantitatively the accuracy of this approach by calculating atomic forces and comparing results with full QM calculations. The impact of the choice made in terminating dangling bonds at the frontier of the QM region is also investigated.

Reliability analysis of mining equipment: A case study of a crushing plant at Jajarm Bauxite Mine in Iran

The performance of mining machines depends on the reliability of the equipment used, the operating environment, the maintenance efficiency, the operation process, the technical expertise of the miners, etc. As the size and complexity of mining equipments continue to increase, the implications of equipment failure become ever more critical. Therefore, reliability analysis is required to identify the bottlenecks in the system and to find the components or subsystems with low reliability for a given designed performance. It is important to select a suitable method for data collection as well as for reliability analysis. This paper presents a case study describing reliability and availability analysis of the crushing plant number 3 at Jajarm Bauxite Mine in Iran. In this study, the crushing plant number 3 is divided into six subsystems. The parameters of some probability distributions, such as Weibull, Exponential, and Lognormal distributions have been estimated by using ReliaSoft's Weibull++6 software. The results of the analysis show that the conveyer subsystem and secondary screen subsystem are critical from a reliability point of view, and the secondary crusher subsystem and conveyer subsystem are critical from an availability point of view. The study also shows that the reliability analysis is very useful for deciding maintenance intervals.

Literary Emergence as a Case Study of Theory in Comparative Literature

In his paper, Literary Emergence as a Case Study of Theory in Comparative Literature, Cesar Dominguez constructs an interdisciplinary theoretical model which sheds new light on literary emergence, a phenomenon that defies literary, artistic, and cultural boundaries. Dominguez opens his discussion with a synthesis regarding the state of the question, paying particular attention to the contradictions provoked when an inventory of emerging literatures is attempted and goes on to develop a theoretical framework in which the dynamic processes which define emerging literature are seen relative to world literature. He understands world literature as a mega-system in which emergence finds itself intrinsically linked to the phenomenon of literary change. Thus defined, the smallest systemic units comprising Weltliteratur are identified and the function of the secondary subsystem of codification is analyzed (among these are literatures), forming the impetus for these emerging literatures, as they define themselves in response to the counter-restrictions, redefinitions, and exclusions imposed upon them. The innovative perspective of Dominguez's paper is the questioning of the currency of national literatures within the framework of traditional comparative literature. Cesar Dominguez, Literary Emergence as a Case Study of Theory in Comparative page 2 of 15 CLCWeb: Comparative Literature and Culture 8.2 (2006):

Nonlinear inferential cascade control of exothermic fixed‐bed reactors

AbstractA nonlinear inferential cascade control strategy for a tubular fixed‐bed reactor with highly exothermic reaction is presented. Tight control of exit conversion and stabilization of hot‐spot temperature was achieved over a wide range of operating conditions. A multiple cascade structure was developed by lumping the distributed‐parameter system and partitioning it into three subsystems. Practical issues of implementing the control system are addressed, as well as physical insight and assumptions used for model reduction of each subsystem. The direct synthesis approach for nonlinear control systems is used to design the controllers of the important subsystems separately. A lag was added in the primary subsystem, and fast stabilization of the secondary subsystem was implemented. Unknown temperature states and inlet concentration were estimated by a nonlinear observer from only a few temperature measurements. The control problem of the moving hot‐spot temperature was also addressed. Simulation on an industrial phthalic anhydride fixed‐bed reactor showed that the observer can give excellent dynamic tracking of the reactor. The resulting cascade control system can achieve good set‐point tracking and disturbance rejection performance, which is robust in the presence of measurement error and model mismatch, and superior to a single‐loop control system.

Modeling of control structures for partially controlled plants

The paper deals with the modeling of control structures for plants that are decomposed into a primary and a secondary subsystem. The main interest is the open-loop behavior of the primary system when the outputs of the secondary system are controlled. Exact analytical relationships between models for control structures corresponding to different decompositions, variable transformations and control strategies for the secondary systems are derived. Such models can be used, for example, for screening of control structures based on various steady-state or frequency-dependent controllability measures. Continuous distillation is used as an example in the paper.

Availability and reliability of the system with pre-emptive priorities and shut-off rules

A model involving main standby redundancy and secondary subsystems having pre-emptive repeat priorities is considered. If the secondary subsystem fails when the main subsystem is operating with one functioning unit and one failed unit, then the secondary subsystem starts to be repaired (pre-emptive priority). If both main and secondary subsystems are inoperable, then the main subsystem has high priority for repair. In this model, we obtained the system availability, the mean inter-occurrence shut-off time and steady-state probability that the system is under shut-off by the technique of the Markov renewal process. We also obtained the system reliability by using the Markov chain.

Availability for a [formula omitted]: G subsystem and secondary subsystem subject to shut-off rules

Two-unit series subject to shut-off rules have been treated before. For increasing system availability a new model is considered, which is composed of a 2 3 : G main subsystem and another secondary subsystem. If more than two units of the main subsystem are inoperable, then the main subsystem shuts off the secondary subsystem. For this model, the system availability is obtained by the technique of the Markov renewal process. Then we obtain the mean inter-occurrence shut-off time and the steady-state probability that the system is under shut-off.

Interaction in Primary-Secondary Systems

Primary-secondary systems, consisting of a primary subsystem supporting a relatively light secondary subsystem, are characterized by special dynamic characteristics. One important characteristic is interaction, which is mathematically manifested by coupling between the equations of motion of the two subsystems and results in a reduction in the secondary response. The dynamic analysis of P-S systems is often performed using a decoupled system of equations which is simpler to analyze, but may give overly conservative results leading to unnecessarily costly designs. In this paper, interaction in P-S systems is examined in detail, criteria for assessing the importance of interaction are developed, and the concepts are illustrated with examples of interacting systems.

Availability of standby redundant subsystem and secondary subsystem subject to shut-off rules

Abstract Two-unit series subject to shut-off rules have been treated before. For increasing system availability a new model is considered. The model is composed of a main subsystem which has two units and another secondary subsystem. When one unit of the main subsystem fails, then the other standby unit starts to operate. If both units of main subsystem are unoperable, then the main subsystem shuts off the secondary subsystem. For this model, the system availability is given by the Morkov renewal process. Then we obtain the mean inter-occurrence shut-off time and the steady-state probability that the system is under shut-off.

A case study on evaluation of energy flow and renewable agricultural resources.

本研究は生態学的視点から耕地生産系のエネルギーの流れと利用可能資源の賦存量を茨城県八郷町を例として推定したものである。耕地生産系のモデルは各地帯区分を一つの単位とした。系の主な構成要素は一次生産系, 二次生産系, 土壌系とした。一次生産系におけるエネルギーの流れとしては総生産量, 農産物量, 副産物量, 土壌還元量, 二次生産に利用される量と人為的エネルギー投入量に着目した。また二次生産系におけるエネルギーの流れは総生産量, 畜産物量, 副産物量, 人為的なエネルギー投入量としては飼養に必要な補助的なエネルギー量と系外から搬入した飼料の量に着目して検討した。系外に搬出されるかまたは土壌に還元される副産物量は評価が困難なため検討項目から除外した。一次生産系では一年間に総生産量中に固定された太陽エネルギーは5.79×102 TJ, そのうち農産物量は1.93×102 TJ, 副産物量は2.21×102 TJ, 二次生産に利用された量は2.83×10 TJ, 土壌還元量は1.37×102 TJ, 人為的エネルギー投入量は2.44×102 TJと評価された。農作物の光合成有効放射エネルギーの利用効率は0.52%, 投入エネルギーに対する農産物エネルギー比 (産出/投入比) は0.79と推定された。二次生産系では一年間の総生産量は5.18×102 TJ, そのうち畜産物量は1.34×102 TJ, 副産物量は3.84×102 TJ, 人為的エネルギー投入量のうち, 飼養に要するものは3.49×l0 TJ, 系外から搬入された飼料のエネルギー量は1.03×103 TJと評価された。産出/投入比は0.12と推定された。

Dynamic response of tertiary systems in structures subjected to base excitation

The dynamic response of very lightweight equipment (tertiary subsystem) attached to light equipment (secondary subsystem) which in turn is attached to a heavier structure (primary subsystem) that is subjected to ground shock or earthquake excitation is investigated. Both the single-degree-of-freedom and multi-degree-of-freedom subsystem models are considered. The systems are damped as well as undamped, completely detuned (all natural frequencies of the subsystems well spaced), singly tuned (one natural frequency of each subsystem equal or close to one another), or multiply tuned (more than one natural frequency of the subsystems close to each other). Efficient techniques for the determination of the tertiary subsystem response that avoid a computationally intensive numerical integration of the combined system equations are presented.

Dynamic response of secondary systems in structures subjected to ground shock or impact

The dynamic responses of a variety of multi-degree of freedom primary-secondary systems subjected to ground shock or impact are presented. The systems are damped and undamped. Completely detuned systems (all frequencies of the subsystems well-spaced) as well as singly tuned systems (a natural frequency of the primary subsytem equal or close to a natural frequency of the secondary subsystem) are investigated. The accuracy of the conventional floor spectrum method when applied to primary-secondary systems is presented determined. A new method for the determination of the dynamic response of multiply-tuned primary-secondary systems is presented.

Floor response spectrum method for seismic analysis of multiply supported secondary systems

AbstractFundamental principles from structural dynamics, theory of random processes and perturbation techniques are used to develop a new method for seismic analysis of multiply supported secondary subsystems, such as piping attached to primary structures. The method provides a decoupled analysis of the secondary subsystem wherein the response is given in terms of response spectra associated with the attachment points (‘floors’). In order to account for correlations between modal responses and between support motions, an extension of the conventional floor response spectrum, denoted crossoscillator, cross‐floor response spectrum, is introduced. Important effects of tuning, interaction, non‐classical damping and spatial coupling, which are inherent characteristics of combined primary–secondary systems, are included through the extended spectra. An efficient method for generation of the extended spectra directly in terms of a ground response spectrum is developed.Numerical comparisons with exact results are used to examine the accuracy of the proposed method and to demonstrate the importance of the characteristics mentioned above. In all cases examined, the proposed method shows excellent agreement with exact results. By accounting for the effect of interaction, the proposed method leads to more realistic and economical design criteria for secondary subsystems.

A Systems Analysis of the Remarriage Process:

This reviews of literature focuses on the dynamic interdependence of the process of remarriage. This process includes: (1) the first marriage and its dissolution; (2) the divorced family; (3) mate selection in the remarriage; and (4) the structure of spousal and parental roles in the remarriage. A systems analysis identifies boundary and roles as two constructs implicit in this process. These constructs depend on the functioning and interrelationship of four subsystems: (1) the primary family unit subsystem; (2) the personal subsystem; (3) the interpersonal subsystem; and, (4) the secondary family unit subsystem. Functional remarried families are viewed as systems that develop patterns of interaction that confirm family cohesion adequate role functions and goal consensus. In contrast, dysfunctional remarried families are described as inflexible, lacking a sense of family cohesion, adequate role functions, and goal consensus.

Pharmacokinetics and metabolism of rifampin in humans.

The unique pharmacokinetic properties of rifampin in humans are discussed in this review. These properties can be better understood by assuming the existence of two pharmacokinetic subsystems; one, the primary subsystem, regulates the time course of the concentration of the antimicrobial agent in the other, the secondary subsystem. The first subsystem includes the intestine and the liver (interconnected through the portal blood and the bile), and the second subsystem includes the tissues, kidneys, and blood of the circulatory system. The connection between the two subsystems in normal conditions is the hepatic veins. The rate of excretion of rifampin in human bile depends, although not exclusively, on its rate of transformation into the biologically active desacetyl derivative. The rate of metabolism increases over the first week(s) of treatment, which results in a corresponding increase of desacetylrifampin excretion in bile. The process is limited and, within a given range of single doses, a transport maximum can be identified. Doses in excess of those associated with the transport maximum generate a more than proportional increase in serum concentrations of the drug. Administration of rifampin causes proliferation of the smooth endoplasmic reticulum of the hepatocyte (probably due to glucuronidation of a fraction of rifampin). This observation explains some of the interactions of rifampin with endogenous and exogenous compounds. The unique distribution of rifampin in human tissues probably results from its capacity to cross biological membranes. Excretion of rifampin in urine does not seem to be associated with any active process.