Waste Systems International, Inc. Expands Into Western/Central Massachusetts
LEXINGTON, Mass.–(BUSINESS WIRE)–Sept. 23, 1998–Waste Systems International, Inc. (NASDAQ:WSII), a fully integrated non-hazardous solid waste management company, announced today that it has entered the Western/Central Massachusetts markets through the acquisition of a collection company and transfer station. The combined operations will initially have annualized revenues of approximately $5 million. The Company anticipates integrating these operations with its South Hadley, Massachusetts landfill, which is expected to open during the first half of 1999.
“We are delighted to be adding Western/Central Massachusetts to our existing operations as we strive to build a premier regional fully integrated solid waste management company, primarily focusing on secondary markets,” commented Philip Strauss, WSI’s Chairman and Chief Executive Officer. “The Company has also identified additional acquisitions in the Western/Central Massachusetts markets and expects to close on those opportunities in the near future,” Strauss added.
WSI is an innovative solid waste management company. The Company operates fully integrated solid waste management operations in Central Pennsylvania and Vermont, and is building a fully integrated solid waste management operation in Western/Central Massachusetts and upstate New York. The Company is also evaluating other acquisitions and opportunities primarily in Mid-Atlantic and Northeastern markets.Certain matters discussed in this press release, including statements with regard to acquisition and growth plans, and prospects, are “forward-looking statements” intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. Forward-looking statements are inherently uncertain and subject to risks. Such statements should be viewed with caution. Among the important factors that could cause actual results to differ materially from those indicated by such forward-looking statements are the Company’s ability to manage growth, a history of losses, the ability to identify, acquire and integrate acquisition targets, dependence on management, the uncertain ability to finance the Company’s growth, limitations on landfill permitting and expansion, geographic concentration, and the other risk factors detailed from time to time in the Company’s periodic reports and registration statements filed with the Securities and Exchange Commission. The Company makes no commitment to disclose any revisions to forward-looking statements, or any facts, events or circumstances after the date hereof that may bear upon forward-looking statements.
Arrow Automotive Industries Announces First Quarter Results, Fiscal 1998
FRAMINGHAM, Mass.–(BUSINESS WIRE)–Nov. 5, 1997–Arrow Automotive Industries Inc. (ASE:AI) announced fiscal 1998 first quarter profits with net income of $117,000 on sales of $24,341,000, compared to a net loss of $584,000 on sales of $24,481,000 for the comparable quarter in fiscal year 1997. The operating results for the first quarter of the prior fiscal year included a pre-tax charge of $1,200,000 related to the company’s closing of its California production facility and transferring of the manufacturing operations formerly conducted at that plant to its remaining manufacturing facilities.
Arrow’s president, Jim L. Osment, stated that “the results of operations for the first quarter were in line with the company’s financial forecast.”
Arrow, with headquarters in Framingham, Mass., is one of the nation’s largest remanufacturers of precision replacement parts for domestic and import passenger cars, light and heavy trucks, farm vehicles and off-road industrial and construction equipment. Arrow operates remanufacturing and distribution facilities in South Carolina and Arkansas, as well as distribution warehouses in Canada.
Arrow’s shares are traded on the American Stock Exchange (Symbol: AI). -0- ARROW AUTOMOTIVE INDUSTRIES INC.
CONDENSED STATEMENTS OF OPERATIONS
(IN THOUSANDS EXCEPT PER SHARE DATA)
(Unaudited)
THREE MONTHS ENDED
September 27, September 28,
1997 1996
NET SALES $24,341 $24,481
Income Before Restructuring
Charge and Taxes 117 258
Restructuring Charge (1) 0 (1,200)
Income (Loss) Before Taxes 117 (942)
Provision (Benefit) For Income
Taxes 0 (358)
NET INCOME (LOSS) $117 ($584)
NET INCOME (LOSS) PER SHARE $0.04 ($0.20)
Average Number of Shares
Outstanding 2,873,083 2,873,083
(1) Represents restructuring costs to close the company’s
California production facility and transfer its manufacturing
operations to the company’s remaining facilities.
Fitchburg assets sold; Beloit to operate mill
Beloit Corp. will operate the now-shuttered Fitchburg, Mass., air-dried 440 tpd market deinked pulp (MDIP) mill when it reopens at an as yet unspecified date, producing a still-to-be-determined product.The assets of the facility were sold to the newly formed Massachusetts Paper Co. in early November following an August bankruptcy filing. The mill shut down in September 1996-following a January 1996 startup-amid operational and financial disputes between turnkey contractor Beloit and parent International Recycling Corp. (an entity of Intercontinental Energy Group). At the time, the mill was known as Northeast Recycling Assn. Corp. or Massachusetts Recycling Assn. Corp
The Fitchberg property was transferred subject to existing liabilities, with Beloit reportedly relinquishing its claims for operations and maintenance fees; no cash was paid into Massachusetts Recycling, according to a source. Beloit was expected to take over operations in November 1997. Beloit senior counsel Jack Fishman, listing a wide range of possible pulp and paper industry products, said there has been no decision yet; he did say the latest discussions have focused on tissue and some MDIP Fishman said Beloit will start staffing the facility soon, but he did not know when a decision would be made regarding the startup.
Domtar Inc.’s proposed 772 tpd recycled bleached corrugated (RBC) pulp project in Everett, Wash., should be considered canceled, since the likelihood of its reaching fruition is now “one chance out of 10 or 20,” said a company executive. Domtar has been evaluating the proposal for some time.An MDIP-proposed project at the same site-Snohomish River Pulp Co., which would have involved some common infrastructure with Domtarwas shelved in 1997.
Nor’Easters of VR-62, The
Originally called the Motowners VR-62 was establsihed in 1985 at NAF Detroit, Michigan flying C-9B Skytrain IIs in support of Commander, Fleet Logistics Support Wing. The Motowners became the “Mass Tansport” nine years later upon their transfer to NAS South Weyouth, Massachusetts where they transitioned to C-130T Hercules transports, the aircraft they currently fly. VR-62 detachments were subsequently sent to Sigonella, Sicily and Atsugi, Japan.
Due to BRAC, South Weymouth was closed and VR-62 moved to is current home, NAS Brunswick, becoming the Nor’Easters in 1996. The squadron continues to support worldwide Naval operations. As LCDR James Corey of the squadron puts it, “VR-62 is a Naval Air Reserve squadron but we operate 365 days a year vice being weekend warriors.”
VR-62 has transported more than 12,000 passengers and over 11.6 million pounds of cargo since receiving the C-130Ts.
Among many Nor’Easter accolades are four Noel Davis Battle Es, two James M. Holcombe Maintenance Excellence Awards, two CNO Safety Ss, two Fleet Logistics Support Wing Training Excellence Awards and two ADM Phil Smith Operational Excellence Awards.
Commanding the Nor’Easters is CDR Robert R. Smith. His XO is CDR Christopher S. Chambers. The OiC is CDR Mark W. Samuels. The prospective XO (in May 2004) is CDR Mark O. Howell.
Beijing seeks investors in growing metro
METRO projects in the Chinese capital, Beijing, are leading a reform programme for franchising and investing in infrastructure construction. An historic step was taken in December 2004 when the Municipal Construction Committee announced the offer to non-governmental investors of a 30-year operating franchise for Line 4.Public bidding for lines 5 and 10 got underway last month. The government will transfer the right to manage these lines to the winners for a 20-year operating concession as soon as they are completed in 2007 and 2008 respectively. Total investment for lines 4, 5, and 10 is about $US 4.8 billion.
Two joint ventures are bidding for the Line 4 concession–Hong Kong Mass Transit Railway Corporation with Beijing Infrastructure Investment, and Beijing Capital Group; and Siemens with China Railway Construction Corporation and Beijing Metro Corporation. The winner will also have to pay about Yuan 5 billion ($US 604.1 million), which represents about one-third of the construction costs for the line.
Mr Wang Qi, general manager of the Beijing Municipal Infrastructure Investment Company, added that the municipal government was considering extending the franchise concept to other new lines in the future. The city plans a 350km metro network by 2015.
Bush to press Roh to implement sanctions on N. Korea
U.S. President George W. Bush said Friday he will press South Korean President Roh Moo Hyun to implement a U.N. Security Council sanctions resolution against North Korea when they meet Saturday on the sidelines of an annual Asia-Pacific summit in Hanoi.
”I’ll, of course, talk to the South Korean president about implementing the…resolution,” Bush told reporters when asked whether he thinks Seoul is sufficiently cooperating on sanctions against Pyongyang.
South Korea said Monday it will neither expand its role in multilateral operations, called the Proliferation Security Initiative, to interdict transfer of weapons of mass destruction and delivery systems nor take any new steps to ”punish” Pyongyang ahead of the six-party talks on North Korea’s nuclear programs.
White House spokesman Tony Snow told reporters that the United States wants to ”have the South Koreans playing a role” in the PSI.
Bush, speaking together with Australian Prime Minister John Howard after their meeting, said the two agreed to raise North Korea as one of the key issues for the summit Saturday and Sunday of the Asia-Pacific Economic Cooperation forum.
”We have a chance to solve this issue peacefully and diplomatically,” Bush said, noting that North Korea has agreed late last month to return to the six-party talks, which have been stalled for nearly a year.
Against this backdrop, Bush said, ”It’s important for the world to see that the Security Council resolutions…are implemented.”
”So part of my discussions will be how to fully implement those sanctions that the world has asked for, but also it’s a chance to set the conditions right so that the six-party talks will succeed,” Bush said.
Snow said Bush and Howard agreed on the need to keep pressure on North Korea until the nuclear issue is resolved diplomatically through the six-party talks.
Bush said he will also raise the issue when he meets bilaterally with his counterparts from China, Japan and Russia — the three other six-party members along with South and North Korea and the United States — on the sidelines of the APEC summit.
The resolution was adopted after North Korea carried out its first nuclear test Oct. 9 following its test-firing of seven ballistic missiles, including a long-range Taepodong-2 missile, in July.
LEAD: Bush fails to win Roh’s full support on PSI against N. Korea
U.S. President George W. Bush failed to win support from South Korean President Roh Moo Hyun on Saturday for fully participating in U.S.-led multilateral efforts to interdict North Korea’s transfer of nuclear and other weapons of mass destruction.
South Korea ”is not taking part in the full scope” of the multilateral operations, called the Proliferation Security Initiative, Roh told reporters along with Bush after their talks on the sidelines of a summit of the Asia-Pacific Economic Cooperation forum in Hanoi.
But Roh noted, ”We support the principles and goals of the PSI and will fully cooperate in preventing WMD material transfer in the Northeast Asian region.”
Despite the South Korean rejection, Bush did not make any tough comments on Roh’s position, apparently out of political considerations, merely saying, ”I appreciate the cooperation we’re receiving from South Korea.”
White House spokesman Tony Snow later told reporters that Bush understands ”political constraints” in South Korea, noting that in the U.S. midterm elections on Nov. 7, Bush’s Republican Party lost control of Congress to the Democrats for the first time in 12 years.
The meeting came after South Korea said Monday it will neither expand its role in the PSI nor take any new steps to ”punish” Pyongyang ahead of the six-party talks on North Korea’s nuclear programs.
Snow refused to characterize Roh’s remarks when repeatedly asked whether the United States is satisfied.
But when asked whether the United States expects South Korea to interdict North Korean vessels, Snow said Roh ”did indicate that there were some movements within his government but he did not specify.”
The South Korean rejection came as a major diplomatic setback for the Bush administration, which has been working to make sure that other nations continue to implement sanctions and stop North Korea’s weapons proliferation until Pyongyang returns to the six-party talks and takes ”concrete” steps to abandon its nuclear programs.
Bush has repeatedly warned North Korea against selling nuclear arms to other nations or non-state entities such as terrorists, saying Washington would consider it a ”grave threat” and hold Pyongyang ”fully accountable” for the consequences.
Roh said he and Bush agreed to ”fully support” a U.N. Security Council sanctions resolution adopted against North Korea after it conducted its first nuclear test Oct. 9 following its test-firing of seven ballistic missiles, including a long-range Taepodong-2 missile, in July.
”Our two countries will implement this resolution in a faithful manner,” Roh said.
Roh said he and Bush also agreed to ”actively seek to resolve the North Korean nuclear issue within the six-party talks framework, and also by actively engaging in bilateral talks within this framework.”
Bush said, ”Our desire is to solve the North Korean issue peacefully.”
”We want the North Korean leaders to hear that if it gives up its weapons, nuclear weapons ambitions, we would be willing to enter into security arrangements with the North Koreans, as well as move forward new economic incentives for the North Korean people,” Bush said.
Snow also emphasized that doing so would lead to formally ending the 1950-1953 Korean War, and said Bush sees ”a moment of opportunity” as North Korea agreed late last month to return to the six-party talks, which have been stalled for a year.
Bush and Roh agreed not to tolerate a nuclear North Korea, U.S. and South Korean officials said.
China, South Korea, Japan, Russia and the United States are working to set the stage for North Korea to come back to the table and resume the six-party talks possibly in early December.
The officials said Bush and Roh also discussed the ongoing bilateral negotiations to conclude a free trade agreement as well as Iraq and other Middle East issues.
Model-Based Optimization Drives Mill Profitability, Product Quality
Advanced process control such as model-based analysis, virtual sensors, and model predictive control are now able to impact more aspects of pulping and papermaking
Global competition and escalating raw material and energy costs have forced pulp and paper manufacturers to continuously seek improved efficiencies and lower costs in their operations, while at the same time producing higher quality, more consistent products. Systems and techniques are needed that enable process managers and operators to run their production lines within strategic constraints based on costs, quality, and demand criteria.
One set of emerging applications that delivers on these needs is advanced process control based on model predictive control (MPC) technology. This technology has been utilized for years in many process industries and more recently has moved into pulp mill operations. Now, improved information and control systems are providing the opportunity to extend these applications further into the papermaking process. High quality and robust process models incorporating detailed first principles of pulping and papermaking operations, as well as data driven artificial intelligence techniques, are a key source of systems analysis and online process optimization.
Multivariable process models are now being deployed to improve understanding and control of unit operations as well as entire plants, both in offline and online applications. Solutions currently in use include:
* Model-based multivariable process analysis
* Benchmarking
* Virtual sensors
* MPC
Through innovative product applications, MPC helps paper-makers improve and optimize their processes with low-risk high-return projects. From multivariable analysis and bench-marking to online virtual sensors and controls, process model applications provide the next step in process optimization.
MPC-based applications can be used to optimize specific unit operations or applied across entire operations. With a focus on improved quality and reduced variable costs, these applications will greatly improve paper mill operations in the coming years. Voith Paper Automation provides model-based analysis and optimization through its WebProfit optimization products and services. These applications are delivered as integrated solutions with OnQ quality control system (QCS) installations and OnControl distributed control system (DCS) packages or as stand-alone optimization to legacy systems.
The Growing Meed for Process Optimisation
The business case for new techniques in process optimization has been clearly driven over the past several years by market forces. Increased global competition and higher raw material and energy costs have forced pulp and paper producers to continuously focus on doing more with less. At the same time, converters and end users are demanding better performance and more consistent quality from the products they use.
Under these increasing demands, consistent profitability and even survival of many pulp and paper producers requires improved efficiency and utilization of resources. Beyond basic production procedure and maintenance improvements, sophisticated process optimization approaches hold the key to competitive advantage in today’s global marketplace.
Systems and techniques are needed that enable production lines to run at strategic constraints based on costs, quality, and demand criteria. Typically, the targets of advanced optimization practices are:
* Increased throughput
* Reduced raw material costs
* Reduced energy consumption
* Reduced chemical costs
* Improved quality/reduced variability
Model-Based Optimisation
One approach to process optimization is model-based analysis, prediction, and control. Process models can provide a great deal of information and utility ranging from generalized materials balances through the mill to complex multivariable control of quality properties.
Advanced process control applications have been applied for decades in many continuous and batch process industries. More recently, many pulp mills have applied these same techniques to improve yields and quality based on the ability of these systems to predict results for systems with slow and nonlinear dynamics. Now, improved information technology and measurement systems, including the DCS and robust process historians, are providing the data and connectivity required to extend these advanced process control applications throughout the entire papermaking process.
The preferred process modeling technique is based on first principles knowledge of energy and mass transfer throughout the process. First principles models provide stable and robust descriptions of a process throughout its entire range of operation. However, in a complex system such as a paper machine where all initial conditions are not fully known and where outcomes are affected by unmeasured external influences, equation-based models cannot always accurately describe the process.
Process models can combine process knowledge required to create first principles models with historical data and artificial intelligence, such as neural networks and genetic algorithms. Such models can lead to significant improvements in understanding, control, and profitability. This approach can be used to improve specific unit operations or can be implemented mill-wide.
High value migrants: talent mobility and international development
THE TRAVAILS AND VICISSITUDE OF THE INTERNATIONAL MIGRATION of poor people often make the headlines of the popular press. However, there is another side to the overall migration process that can be termed as the mobility of “high-value migrants”. This process is far less numerous, faces easier immigration rules in developed countries and can lead to a greater economic potential in the development of new technologies and the creation of business, as well as the international transfer of knowledge and best practices. The process can be recognized by the movement across national boundaries of technology experts, software and hardware developers, scientists, entrepreneurs, international managers, etc. In a joint project between the World Institute for Development Economics Research of the United Nations University (UNU-WIDER) in Helsinki, Finland, and the United Nations Economic Commission for Latin America and the Carribbean (UN-ECLAC) in Santiago, Chile, this process has been described as the international mobility of talent. The project has studied the nature, causes and consequences of such mobility for international development.
Talent–an individual’s inner capacity to develop ideas and concepts, some with high economic value–is a critical engine for growth and development. It is an area in which developing countries usually lag behind developed nations and where development gaps are more evident. The “human factor” is critical to the success or failure of many endeavours. Emerging economies, such as China, India, the Russian Federation and Poland and to a lesser extent some Latin American countries, are becoming an important source of talented people like engineers and technical experts, some of whom have doctorate degrees from top-level universities.
Part of the new talent in developing countries goes to live and work in developed countries, typically in the United States, the United Kingdom and other nations of the Organization for Economic Cooperation and Development. This creates a concern over the ensuing loss of scarce human capital that would be deployed for the development of the knowledge economy in home countries. However, talented individuals also return home after graduation or after years of work in the host country, often bringing with them new knowledge, technologies, capital and contacts that are all very useful for national development. The traditional concept of “brain drain” must therefore be re-examined in light of the increasing interdependence and mobility of people among countries in response to new opportunities (and risks) that are offered by globalization. This leads to a new emphasis on brain circulation.
Today we see various patterns of international mobility of talent and capital around the world. On the one hand, talent from developing countries is moving north and seeking better opportunities in economies where people are equipped with more capital, technologies and effective organizations. On the other hand, capital from the north pursues talent in the south, setting up plants in countries where talent is readily available and cheaper than in developed nations. In turn, south-south migration of capital and talent is another possibility that is gaining increasing force. In the early twenty-first century, the patterns of mobility of talent have to be studied along with the mobility of capital and technologies, as they usually go together.
Our research has identified several factors that affect the mobility of talent: international differences in earnings and development gaps; the role of job availability, agglomeration and capital in the demand for talent; the role of technology; linguistic compatibility, networks and sociocultural affinity; and the shortage of skills and immigration policies.
International differences in earnings. These differences often reflect development gaps across countries. For example, if a software developer in the Russian Federation makes an income that is just a fraction of what he or she can earn in the United States or the United Kingdom, we can expect this Russian expert to move to a country that will offer a higher salary. Generally, the international mobility of talent depends on the income differential between what can be earned abroad versus the earnings at home. International income per capita differentials across countries are substantial, and large net income differentials certainly prompt emigration to the higher-paying country. This leads us to make a connection between development gaps–the difference in living standards and productive potential among countries–and the direction of the flow of talented individuals. Poor countries are likely to experience an outflow of professionals and entrepreneurs, while middle-income countries can see an outflow of human capital if salaries and benefits are lower than in other countries and the prospects for career development are uncertain. In addition, the outflow of scarce human capital can, by itself, amplify the development gaps, as the departure of human capital and talent can be a negative factor for domestic economic growth, at least in the short run.
Jobs, capital and talent. A country that offers interesting economic opportunities and good living conditions will attract capital, workers and talent. The relation between capital and talent may go in various directions. In a world of international mobility, factors of production capital face several possibilities regarding the use of talent: hiring domestic talent for production and/or marketing; importing talent from foreign countries; relocating operations to low-wage countries to tap talent there; and outsourcing talent services in either foreign countries or the home market. Some configurations of mobility of capital and talent are possible.
Another feature of the use of talent is the existence of agglomeration and concentration effects. In general, talent is attracted by the availability of other skilled persons, as creative processes are rarely done in isolation. Technical experts, engineers and scientists may leave their native countries, not only for better pay abroad but also the allure of interacting with peers of international recognition, and to locate in areas where there are resources to do research and develop new technologies. In contrast, talented individuals in their home countries may find lack of recognition, poor career prospects, modest salaries and the absence of a critical mass of professional peers.
Technology and the demand for talent. The revolution of the information and communications technology (ICT) in the last two to three decades has spurred an increase in the demand for specialized talent. Engineers, programmers, scientists and other experts whose knowledge can be used in the development of software and hardware are especially valuable. When talent is imported, its supply comes from a few developing countries. In turn, the supply of technical talent from Latin or South America for some important markets like the United States is still small in contrast with the talent from Asia. Another point to be made is that ICT allows that services be rendered without a permanent physical presence of the provider; for instance, consultancy reports can be sent and interacted through the Internet, or accounting can be provided electronically.
Linguistic compatibility, networks and sociocultural affinity. High education, knowledge of more than one language and understanding of cultural differences among countries are some qualifications of talented migrants, which can facilitate their international mobility and make their adjustment to other countries and realities easier. Members of the international elite of talent are often educated abroad, belong to professional and alumni networks of prestigious universities, and have developed a dense network of contacts worldwide with well-placed individuals around the world.
Shortage of skilled professionals and favourable immigration policies. The shortage of certain skilled professionals in local labour markets, such as information technology experts, computer science specialists, engineers, nurses and doctors, is an important factor behind the increase in demand for talent in the world economy. Immigration policies in rich countries are much more favourable to international talent than unskilled migrants, thus facilitating the inflow of talent. Newly rich countries, such as Ireland, Singapore and Scotland, are also putting in place immigration policies and offering economic conditions favourable to the admission of migrants with higher education and special know-how, and also investors who bring capital and technology. Advanced countries, such as Australia, the United States, Canada, the United Kingdom and Germany, have created special visa programmes for ICT experts, nurses and doctors, scientists and graduate students, thus competing with developing countries in their efforts to attract or retain talented individuals.
A Mathematical Model for Interplanetary Logistics
This article demonstrates a methodology for designing and evaluating the operational planning for interplanetary exploration missions. A primary question for space exploration mission design is how to best design the logistics required to sustain the exploration initiative. Using terrestrial logistics modeling tools that have been extended to encompass the dynamics and requirements of space transportation, an architectural decision method has been created. The model presented in this article is capable of analyzing a variety of mission scenarios over an extended period of time with the goal of defining interesting mission architectures that enable space logistics. This model can be utilized to evaluate different logistics trades, such as a possible establishment of a push-pull boundary, which can aid in commodity pre-positioning. The model is demonstrated on an Apollo-style mission to both provide an example and validate the methodology.
The development of an interplanetary supply chain requires the unification of two traditionally separate communities: aerospace engineering and operations research. In order to create an effective means of communication between both communities, a distinct terminology has been developed and is detailed extensively in Section I. Specifically, the definition of the commodities or supplies, and the elements or physical containment and propulsion units used to transport the commodities are detailed. Furthermore, the network definition is presented as well as the definition and description of the time expanded network, which is the terrestrial modeling technique employed for the space logistics model. Section II describes the components of the interplanetary logistics problems. Section III presents the problem formulation and constraints. In Section IV a description of the optimization methodology developed to solve this problem is discussed. In Section V the problem formulation and solution methodology is applied for the example of an Apollo-style mission to both explain the implementation and validate the methodology presented. Section VI reviews the contributions of this article and describes continuing work in this area.
I. Problem Definition
The goal of the interplanetary logistics problem is to determine feasible mission architectures to satisfy the demand generated by the needs of exploration. The key concept of the interplanetary logistics problem is that the demand of crew, consumables, equipment and other exploration requirements at in-space locations drives the mission requirements. Therefore, the first required input for the interplanetary logistics problem is the definition of these supplies. For example, if the exploration mission is a sortie style mission to investigate a particular location, the demand might consist of a few crew members at a specific location and the supplies necessary to both support the crew and enable the exploration activities.
Given the demand of the mission, it is necessary to determine how and when the supplies on Earth will be transported to the in-space locations. As missions become more complex and evolve over a period of time, a solution may become less obvious. Since the goal is to minimize the cost of any mission, it is desirable to optimize the timing and method of transport of the supplies to in-space locations. Therefore, it is necessary to define all pathways and structures used for transport, and allow the optimizer to analyze the different architectures to select the best one.
Given this information, the interplanetary logistics problem can determine low cost mission architectures that satisfy the exploration demand. The solution generated will detail the scheduling and assignment of supplies to vehicles for in-space transport and launch scheduling requirements. More importantly, however, the output of this problem can be used to determine a push-pull boundary for the supplies, the potential of a specific location, either on a surface or in-space for storing supplies, benefits of in-situ resource utilization over multiple missions, or even the sensitivity of mission architectures to changes in vehicle parameters.
The first step in developing a model for interplanetary logistics is defining a concrete nomenclature that describes the components of the problem. The problem fundamentally consists of three components: the commodities or supplies that must be shipped to satisfy a mission demand, the elements or physical structures used to both hold and move the commodities, and the network or pathways the elements and commodities travel on. The following sub-sections define the parameters that describe each of these components.
The goal of the space logistics project is to determine how to meet the demand for the exploration missions. As such, we are investigating how to optimally ship multiple types of commodities. For the purpose of the logistics problem, a commodity will be defined as a high-level aggregate of a type of supply, such as crew provisions. Thus, we will define a set of k = 1,…, K commodities, each with the following parameters:
* Denote the demand of each commodity as d^sup k^.
* Denote the origin of each commodity as so^sup k^.
* Define the destination of each commodity as sd^sup k^.
* Define the availability interval of each commodity as to^sup k^ = [sto^sup k^, eto^sup k^], where sto^sup k^ is the starting time of the interval and eto^sup k^ is the ending time of the interval.
* Define the delivery interval of each commodity as td^sup k^ = [std^sup k^, etd^sup k^], where std^sup k^ is the starting time of the interval and etd^sup k^ is the ending time of the interval.
* Define the unit mass of each commodity as m^sup k^ when it arrives at the destination.
* Define the unit volume of each commodity as v^sup k^ when it arrives at the destination.
* Define the number of specified waiting sequences as nw^sup k^.
By defining a waiting sequence as part of the commodity input, a number of wait arcs along the path can be specified, which allows onroute destinations to be designated. For each waiting arc sequence I where 0
* Define the static node of the wait sequence as sw^sub l^^sup k^.
* Define the required waiting time period as pw^sub l^^sup k^.
* Define the wait interval for each wait sequence as = [tw^sub l^^sup k^, etw^sub l^^sup k^], where stw^sub l^^sup k^ is the starting time of wait interval l of commodity k, etw^sub l^^sup k^ is the ending time of wait interval l of commodity k, and etw^sub l^^sup k^ - stw^sub l^^sup k^ ? pw^sup l^^sup k^.
It is important to note that in this model a crew member is treated as a commodity. In practice crewed missions are treated differently during mission planning: however, for the purposes of the architectural design tool created by this model, crew can be considered a commodity with highly restrictive parameter values. By narrowing the availability and delivery windows for a crew commodity, the feasible shipment pathways are limited and reasonable architectures for crewed flights can be obtained.
Elements
In order to ship the commodities from the origin to the destination locations, we require ‘containers’ to both hold the commodities and provide propulsion to move the mass through space. These components can be abstracted to a single definition of an element. Elements are physical, indivisible functional units that transport the commodities from origin to destination. An element is classified by the amount of commodity capacity and propulsive capability it possesses. Elements can be divided into two classes: non-propulsive elements M^sub N^ and propulsive elements Mp. The element parameters are (Figure 1) as follows:
* The maximum fuel mass of a propulsive element m, m euro M^sub p^ is denoted by mf^sup m^.
* The specific impulse of the fuel in element m is denoted by I^sub sp^^sup m^.
* The structural mass of element m is denoted by ms^sup m^.
* The mass capacity of element m is denoted by CM^sup m^.
* The volume capacity of element m is denoted by CV^sup m^.
* The cost of element m is denoted by Cost^sup m^.
Networks
In order to transfer the commodities and elements from the origin node to the destination node, the trajectories must be defined. The purpose of the interplanetary logistics model developed in this article is to analyze the multiple choices available for routing all of the commodities and elements to determine the best logistics architecture. To model the different available trajectories, a network model of space is created to represent the possibilities available for transferring commodities to their respective destination. The following sections detail the development of the space network utilized to form the model presented in this article.