The era of "just-in-time" inventories, in which everyone from manufacturers to retailers kept as little inventory on hand as possible, may be coming to an end.

That could leave companies like automobile manufacturers that rely on so called just-in-time inventories with a crimp in their supply lines.

It would severely affect those companies that depend on just-in-time inventory.

But by now, the terms of Japan's production techniques - just-in-time inventories, zero defects and continuous improvement - are familiar to American manufacturers.

Many American retailers have adopted "just-in-time" inventory controls to improve efficiencies and reduce costly inventories.

Energy officials said they plan to study the use by oil companies of just-in-time inventories, the practice of keeping only enough supplies on hand to meet anticipated needs.

The shipyard also introduced a modified form of the Japanese innovation called just-in-time inventory, which relies on streamlined delivery of parts to cut down on storage costs.

"The real value is just-in-time inventory," Dr. Hamilton said.

He studied the Toyota Corporation's "just-in-time" inventory control and adapted it to Alcoa.

"For example, the preference for just-in-time inventory could turn into just-in-case, and we could see an inventory buildup," he said.