Performance Analysis of Duty-Cycle Division Multiplexing for Optical Fiber Communication Systems

The ever increasing demand for network capacity motivates the explorations for new modulation formats and multiplexing techniques. Wavelength division multiplexing (WDM) channel capacity can be improved by using time division multiplexing (TDM). However, TDM requires precise bit and symbol synchronization and limited from the operating speed of electronic components. The introduction of return-tozero (RZ) line coding facilitates TDM synchronization in high speed transmission systems. Alternatively WDM channel capacity can be doubled by using polarization division multiplexing (PDM) or differential quadrature phase-shift-keying (DQPSK) modulation format. Duty-cycle division multiplexing (DCDM) is another multiplexing technique that can support multiple users per WDM channel. Previously, initial version of DCDM (IVDCDM) is proposed for optical fiber communications. DCDM takes advantage of RZ and offers even better synchronization at the lower clock frequency with smaller spectral width. However, IV-DCDM is badly affected from the fiber chromatic dispersion (CD). In addition, it requires high optical signal-to-noise ratio (OSNR) and less tolerance to self-phase modulation (SPM). For implementation, the IV-DCDM architecture required n modulators for n channels at the multiplexer and n + 1 sampling circuits at the receiver, which is not economically efficient. In this study, the design of DCDM multiplexer and demultiplexer is improved. A new set of algorithm are developed for data recovery in the receiver. At the same time, a model for BER estimation based on the decision algorithms is established. Performance of the proposed demultiplexer with the new decision algorithm is evaluated using the same multiplexer design used in IV-DCDM. Since in the improve setup the multiplexer operates in optical domain this system is referred to as O-DCDM. Using the O-DCDM, performance of IV-DCDM is improved significantly by around 40 times in terms of CD tolerance, 6.5 dB better OSNR and around 3 dB higher SPM threshold. The number of sampling circuits is also reduced by one count in the proposed demultiplexer, which leads towards design simplification. Performance of the proposed multiplexer architecture is evaluated together with the proposed demultiplexer. Since the proposed multiplexer operates in electrical domain this system is referred to as E-DCDM. Using the E-DCDM, the numbers of required modulators are reduced to only one regardless of the number of user. Using EDCDM, performance of IV-DCDM is improved by around 48 times in terms of CD tolerance, 1.6 dB better OSNR and around 4.5 dB higher SPM threshold. Performance of E-DCDM is improved further by using amplitude distribution controller (ADC). Using E-DCDM with ADC, referring to IV-DCDM, performance is improved by around 46 times in CD tolerance, 7.5 dB better OSNR and 3.5 dB more SPM threshold. Based on these developments, performance of DCDM is comparable against the available multiplexing and modulation techniques with an advantage, which is simpler transmitter and receiver. DCDM can support multiple users per WDM channel without the needs of increasing the clock rate at the receiver. Using this technique, 7 × 10 Gb/s is transmitted over 139 km and recovered by using 10 GHz clock

Robust Multi-Objective Sustainable Reverse Supply Chain Planning: An Application in the Steel Industry

In the design of the supply chain, the use of the returned products and their recycling in the production and consumption network is called reverse logistics. The proposed model aims to optimize the flow of materials in the supply chain network (SCN), and determine the amount and location of facilities and the planning of transportation in conditions of demand uncertainty. Thus, maximizing the total profit of operation, minimizing adverse environmental effects, and maximizing customer and supplier service levels have been considered as the main objectives. Accordingly, finding symmetry (balance) among the profit of operation, the environmental effects and customer and supplier service levels is considered in this research. To deal with the uncertainty of the model, scenario-based robust planning is employed alongside a meta-heuristic algorithm (NSGA-II) to solve the model with actual data from a case study of the steel industry in Iran. The results obtained from the model, solving and validating, compared with actual data indicated that the model could optimize the objectives seamlessly and determine the amount and location of the necessary facilities for the steel industry more appropriately.This article belongs to the Special Issue Uncertain Multi-Criteria Optimization Problem

Investigating the impact of networking capability on firm innovation performance:using the resource-action-performance framework

The author's final peer reviewed version can be found by following the URI link. The Publisher's final version can be found by following the DOI link.Purpose The experience of successful firms has proven that one of the most important ways to promote co-learning and create successful networked innovations is the proper application of inter-organizational knowledge mechanisms. This study aims to use a resource-action-performance framework to open the black box on the relationship between networking capability and innovation performance. The research population embraces companies in the Iranian automotive industry. Design/methodology/approach Due to the latent nature of the variables studied, the required data are collected through a web-based cross-sectional survey. First, the content validity of the measurement tool is evaluated by experts. Then, a pre-test is conducted to assess the reliability of the measurement tool. All data are gathered by the Iranian Vehicle Manufacturers Association (IVMA) and Iranian Auto Parts Manufacturers Association (IAPMA) samples. The power analysis method and G*Power software are used to determine the sample size. Moreover, SmartPLS 3 and IBM SPSS 25 software are used for data analysis of the conceptual model and relating hypotheses. Findings The results of this study indicated that the relationships between networking capability, inter-organizational knowledge mechanisms and inter-organizational learning result in a self-reinforcing loop, with a marked impact on firm innovation performance. Originality/value Since there is little understanding of the interdependencies of networking capability, inter-organizational knowledge mechanisms, co-learning and their effect on firm innovation performance, most previous research studies have focused on only one or two of the above-mentioned variables. Thus, their cumulative effect has not examined yet. Looking at inter-organizational relationships from a network perspective and knowledge-based view (KBV), and to consider the simultaneous effect of knowledge mechanisms and learning as intermediary actions alongside, to consider the performance effect of the capability-building process, are the main advantages of this research

Evaluating strategies for implementing industry 4.0: a hybrid expert oriented approach of B.W.M. and interval valued intuitionistic fuzzy T.O.D.I.M.

open access articleDeveloping and accepting industry 4.0 influences the industry structure and customer willingness. To a successful transition to industry 4.0, implementation strategies should be selected with a systematic and comprehensive view to responding to the changes flexibly. This research aims to identify and prioritise the strategies for implementing industry 4.0. For this purpose, at first, evaluation attributes of strategies and also strategies to put industry 4.0 in practice are recognised. Then, the attributes are weighted to the experts’ opinion by using the Best Worst Method (BWM). Subsequently, the strategies for implementing industry 4.0 in Fara-Sanat Company, as a case study, have been ranked based on the Interval Valued Intuitionistic Fuzzy (IVIF) of the TODIM method. The results indicated that the attributes of ‘Technology’, ‘Quality’, and ‘Operation’ have respectively the highest importance. Furthermore, the strategies for “new business models development’, ‘Improving information systems’ and ‘Human resource management’ received a higher rank. Eventually, some research and executive recommendations are provided. Having strategies for implementing industry 4.0 is a very important solution. Accordingly, multi-criteria decision-making (MCDM) methods are a useful tool for adopting and selecting appropriate strategies. In this research, a novel and hybrid combination of BWM-TODIM is presented under IVIF information

Effect of optical filtering on the performance of 40 Gbps DCDM systems

The effect of optical filtering on 40 Gbps on-off keying over 2 x 20, 3 x 13.33, 4 x 10, and 7 x 5.714 Gbps duty-cycle division multiplexing (DCDM) is investigated. The system can tolerate down to 30 GHz optical filter bandwidth for 2 users, and 47.5 GHz for 7 users. At this bandwidth, 40 Gbps was successfully transmitted over 464 km and 193 km SSMF using 2 and 7 users, respectively

A Survey of Perceptions and Expectations of Citizens from Improvement of Villages to City and Its Effect on the Quality of Urban Services

One of the most important factors that citizens are faced after turning a village to a city is the quality of presented services from urban management. The present study aimed to obtain an exact description of the distance between perceptions and expectations of citizens of Fazel Abad of the quality of urban services.  The study is descriptive-survey by field method. Study population is all citizens of Fazel Abad city using urban services and the sample size based on Cochran’s formula is 375 and they were studied by simple random method. The study findings showed that there was a significant difference between perceptions and expectations of citizens to presenting urban services and the highest gap mean (-3.31) of social indices and the lowest gap mean (-1.21) were dedicated to environmental indices

Modeling of environmental aspects related to reverse osmosis desalination supply chain

open access journalBackground: This study aimed to model optimization of strategic environmental management decisions in the operation of reverse osmosis desalination, emphasizing the costs required for the environmental protection during the production of freshwater using reverse osmosis technology. Methods: This analytical research was conducted in five cities of Hormozgan province in Iran for 18 months from February 2018 to September 2019. The research includes eight phases of defining the research problem, data collection, preliminary data analysis and decision criteria, mathematical modeling, model validation, information preparation, analysis and finally discussion, conclusions and suggestions. The main environmental issues were the carbon dioxide (CO2) release rate due to power demand and rejected brine water (RBW) were entered the mathematical model. Results: The desalination plants of Abu Musa, Bandar Abbas, Qeshm, Sirik, and Hormoz with water production flow rate of 2100, 89 000, 5300, 3300 and 1500 m3/d can generate 2360.82, 100053.80, 5958.260, 3709.86 and 1686.30 tons/year of CO2 emissions respectively. This output requires 1.35, 57.47,3.42, 2.13 and 0.97 million USD for controlling the process, respectively. For reduction of the negative effect of RBW 0.75, 22.79, 1.78, 1.15 and 0.55 million USD respectively, is needed. Conclusion: Recommendations for environmental impacts protection of RBW, for desalination capacity up to 50 000 m3/d, are; (a) for desalination capacity up to 50 000 m3/d; dilution the RBW using raw water before entering into the sea, (b) for capacity of 50 000-100 000 m3/d; dispersing RBW in sea using diffuser, and (c) for capacity more than 100 000 m3/d; hybrid water desalination plants and power plant. Application of power plant cooling water to dilute RBW may reduce cost

A Survey of Perceptions and Expectations of Citizens from Improvement of Villages to City and Its Effect on the Quality of Urban Services

One of the most important factors that citizens are faced after turning a village to a city is the quality of presented services from urban management. The present study aimed to obtain an exact description of the distance between perceptions and expectations of citizens of Fazel Abad of the quality of urban services.  The study is descriptive-survey by field method. Study population is all citizens of Fazel Abad city using urban services and the sample size based on Cochran’s formula is 375 and they were studied by simple random method. The study findings showed that there was a significant difference between perceptions and expectations of citizens to presenting urban services and the highest gap mean (-3.31) of social indices and the lowest gap mean (-1.21) were dedicated to environmental indices