Tuesday, November 20th, 2012

Time	Event
5:00a	What can logistics do for you? A couple of decades ago, visitors to the quiet city of Zaragoza, Spain, had no reason to think it would become a capital of world trade. But in 2000, the city opened Europe’s largest logistics hub, called PLAZA — and now Zaragoza is a key global shipping link, connecting manufacturers, suppliers and distributors, among others involved in international commerce. Fish caught off the coast of Namibia, in Africa, are flown to Zaragoza before being sold around the Iberian peninsula; clothes made in Portugal stop in Zaragoza en route to Asia. Meanwhile, the presence of the transportation hub has convinced more businesses to locate themselves near the city. “It is a positive feedback loop,” says Yossi Sheffi, the Elisha Gray II Professor of Engineering Systems at MIT and author of a new book on the growth of logistics hubs and their role in driving economic growth. In places such as Zaragoza, he says, there is “a self-reinforcing mechanism where the logistics cluster grows, providing lower costs and a higher level of service to the companies there, attracting even more companies, making the location even more attractive, providing more and more jobs.” Spanish officials believe PLAZA employs about 10,000 people, and its presence has created many other jobs around the logistics park. Sheffi’s book, “Logistics Clusters: Delivering Value and Driving Growth,” published this fall by MIT Press, explores how many cities, including seemingly unfashionable metropolises such as Zaragoza — or Rotterdam, in the Netherlands, and Memphis, Louisville and Indianapolis in the United States — have turned themselves into 21st-century economic winners by carving out an important role for themselves in global trade networks, even as similar areas grapple with industrial decline. It is a strategy, Sheffi thinks, that other city and regional officials would be wise to consider — partly because, he says, the benefits of having a logistic cluster in a region can be spread out widely within a city’s population. The shipping industry employs a wide variety of workers and provides opportunities for professional advancement. “Jobs in logistics create social justice,” Sheffi says. “There is huge upward mobility, because this industry values on-the-floor experience. Almost every company that I visit hires from within — and if not within the company, they invariably hire from within the industry.” If you build it, they will come In surveying cities that have become global freight hubs, Sheffi finds that there is no one template for success, in infrastructure or geographic location; cities that have become logistics centers have generally just aggressively taken advantage of the assets they do have. Zaragoza, for instance, is 150 miles from the coast, and not especially close to either Madrid or Barcelona, Spain’s biggest cities. But it does have a central location, and a major military airport that the United States built in the 1950s. Spain took control of the airfield in the 1990s, giving Zaragoza long, heavy-duty runways suitable for 747s and other large planes. Memphis (home of FedEx) and Louisville (where UPS has its major operations) have followed a similar path by developing air-freight operations. On the other hand, many cities — including Los Angeles, Rotterdam, Sao Paulo and Singapore — have built around their major ports to become even larger freight hubs However they originate, Sheffi finds that successful logistics clusters share common elements in their growth. Industrial firms will relocate distribution centers to be near the transportations hubs. More companies will follow, leading to a higher frequency of movements: more flights, trains, trucks and ships. As shipping volume grows, the transportation companies can move goods with a lower cost per shipment. Logistics firms can add new services for their partner firms: UPS handles repair and return work for Toshiba, for instance. This means logistics clusters often contain technical jobs beyond those strictly related to shipping; the average salary in logistics, Sheffi observes, is comparable to that in manufacturing. All this growth, Sheffi adds, can lead to political clout for logistics firms and additional government investment in infrastructure. Being big thus helps a logistics cluster get even bigger: The Memphis area ranks No. 43 in the United States by population, but is ranked first in air freight, third in rail freight, and fourth in inland barge freight. The city’s airport is responsible for 220,000 jobs. Moreover, as Sheffi says, “These jobs cannot be offshored. You have to run distribution locally.” Success in logistics can create clusters of companies in other areas. Indianapolis has a growing life-sciences cluster; Memphis has a large cluster of firms that make medical devices. As in all types of industry clusters, Sheffi notes, “These firms benefit from the labor force with specific expertise. There is a significant knowledge exchange, and there are many opportunities for collaborative operations which reduce the costs and improve the service levels offered by companies in the cluster.” The limits of logistics growth “Logistics Clusters” caps several years of research by Sheffi, who directs the MIT Center for Transportation and Logistics. Michael Porter, a professor at Harvard Business School, has called the new book “a fascinating description of the power of [logistics] clusters” that shows how they “are getting more important in the global economy, not less.” Still, Sheffi points out that there are limits to logistics clusters as drivers of economic development; not every place can be Memphis, after all. He sees two main limits to the positive-feedback loops some cities have experienced based on transportation. One involves the constraints of physical space in urban areas: Zaragoza grew rapidly, in part, because Barcelona, bordering water, could not expand as a transportation hub in the same way. Another limitation is environmental: More commercial activity means greater potential for pollution, noise and congestion. For this reason, Sheffi says, some logistics hubs are becoming leaders in environmental sustainability: The port of Los Angeles uses alternative-fuel trucks and has funded development of zero-emissions trucks, while Rotterdam and Singapore are the two largest producers of biofuels in the world. Chicago has invested in infrastructure to reduce congestion by eliminating many railroad crossings. Ulitmately, Sheffi notes, logistics clusters not only enable trade to occur, but their presence can spur more of it. Even given the rocky economic patch of the last few years, Sheffi concludes in the book, in the long run there will almost certainly be a need for more and better nodes in the global freight transportation network: “Growth may happen in fits and starts but, surely, it will happen.” (Comment on this)
5:00a	Making ‘nanospinning’ practical Nanofibers — strands of material only a couple hundred nanometers in diameter — have a huge range of possible applications: scaffolds for bioengineered organs, ultrafine air and water filters, and lightweight Kevlar body armor, to name just a few. But so far, the expense of producing them has consigned them to a few high-end, niche applications. Luis Velásquez-García, a principal research scientist at MIT’s Microsystems Technology Laboratories, and his group hope to change that. At the International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications in December, Velásquez-García, his student Philip Ponce de Leon, and Frances Hill, a postdoc in his group, will describe a new system for spinning nanofibers that should offer significant productivity increases while drastically reducing power consumption. Using manufacturing techniques common in the microchip industry, the MTL researchers built a one-square-centimeter array of conical tips, which they immersed in a fluid containing a dissolved plastic. They then applied a voltage to the array, producing an electrostatic field that is strongest at the tips of the cones. In a technique known as electrospinning, the cones eject the dissolved plastic as a stream that solidifies into a fiber only 220 nanometers across. In their experiments, the researchers used a five-by-five array of cones, which already yields a sevenfold increase in productivity per square centimeter over even the best existing methods. But, Velásquez-García says, it should be relatively simple to pack more cones onto a chip, boosting productivity even more. Indeed, he says, in prior work on a similar technique called electrospray, his lab was able to cram almost a thousand emitters into a single square centimeter. And multiple arrays could be combined in a panel to further increase yields. Surfaces, from scratch Because the new paper was prepared for an energy conference, it focuses on energy applications. But nanofibers could be useful for any device that needs to maximize the ratio of surface area to volume, Velásquez-García says. Capacitors — circuit components that store electricity — are one example, because capacitance scales with surface area. The electrodes used in fuel cells are another, because the greater the electrodes’ surface area, the more efficiently they catalyze the reactions that drive the cell. But almost any chemical process can benefit from increasing catalysts’ surface area, and increasing the surface area of artificial-organ scaffolds gives cells more points at which to adhere. Another promising application of nanofibers is in meshes so fine that they allow only nanoscale particles to pass through. The example in the new paper again comes from energy research: the membranes that separate the halves of a fuel cell. But similar meshes could be used to filter water. Such applications, Velásquez-García says, depend crucially on consistency in the fiber diameter, another respect in which the new technique offers advantages over its predecessors. Existing electrospinning techniques generally rely on tiny nozzles, through which the dissolved polymer is forced. Variations in operating conditions and in the shape of the nozzles can cause large variation in the fiber diameter, and the nozzles’ hydraulics mean that they can’t be packed as tightly together. A few manufacturers have developed fiber-spinning devices that use electrostatic fields, but their emitters are made using much cruder processes than the chip-manufacturing techniques that the MTL researchers exploited. As a consequence, not only are the arrays of tips much less dense, but the devices consume more power. “The electrostatic field is enhanced if the tip diameter is smaller,” Velásquez-García says. “If you have tips of, say, millimeter diameter, then if you apply enough voltage, you can trigger the ionization of the liquid and spin fibers. But if you can make them sharper, then you need a lot less voltage to achieve the same result.” Wicked wicker The use of microfabrication technologies not only allowed the MTL researchers to pack their cones more tightly and sharpen their tips, but it also gave them much more precise control of the structure of the cones’ surfaces. Indeed, the sides of the cones have a nubby texture that helps the cones wick up the fluid in which the polymer is dissolved. In ongoing experiments, the researchers have also covered the cones with what Velásquez-García describes as a “wool” of carbon nanotubes, which should work better with some types of materials. Indeed, Velásquez-García says, his group’s results depend not only on the design of the emitters themselves, but on a precise balance between the structure of the cones and their textured coating, the strength of the electrostatic field, and the composition of the fluid bath in which the cones are immersed. “Fabricating exactly identical emitters in parallel with high precision and a lot of throughput — this is their main contribution, in my opinion,” says Antonio Luque Estepa, an associate professor of electrical engineering at the University of Seville who specializes in electrospray deposition and electrospinning. “Fabricating one is easy. But 100 or 1,000 of them, that’s not so easy. Many times there are problems with interactions between one output and the output next to it.” The microfabrication technique that Velásquez-García’s group employs, Luque adds, “does not limit the number of outputs that they can integrate on one chip.” Although the extent to which the group can increase emitter density remains to be seen, Luque says, he’s confident that “they can make a tenfold increase over what is available right now.” The MIT researchers’ work was funded in part by the U.S. Defense Advanced Research Projects Agency. (Comment on this)

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