The present invention comprises a junction between an unconventional superconductor, an intermediate material, and a conventional superconducting material. In some embodiments, the unconventional superconductor has an orthorhombic crystal structure and the supercurrent in the resulting junction flows in the c-axis direction of the orthorhombic crystal. In other embodiments, the supercurrent flows parallel to a direction in the a-b plane. Interface junctions according to embodiments of the present invention may be used in superconducting low inductance qubits (SLIQs) and in permanent readout superconducting qubits (PRSQs), can form the basis of quantum registers, and can permit parity keys or other devices made from conventional superconducting material to be attached to qubits made from unconventional superconducting material or vice versa. Coherent tunnel junctions according to embodiments of the present invention may be used to form parity keys or to coherently couple two regions of a superconducting material.

This invention relates to structures that have quantum coherence, such as Josephson junctions, and more particularly to their application in superconducting quantum computing.
The quantum computer is rapidly evolving from a wholly theoretical idea to a physical device that will have a profound impact on the computing of tomorrow. A quantum computer differs principally from a conventional, semiconductor chip-based computer, in that the basic element of storage is a xe2x80x9cquantum bitxe2x80x9d, or xe2x80x9cqubitxe2x80x9d. A qubit is a creature of the quantum world: it can exist in a superposition of two states and can thereby hold more information than the binary bit that underpins conventional computing. One of the principal challenges in quantum computing is to establish an array of controllable qubits, so that large scale computing operations can be carried out. Although a number of different types of qubits have been created, it is believed that the practical realization of a large scale quantum computer is most likely to be achieved by harnessing the properties of superconducting junctions. It is in the superconducting regime that many materials display their underlying quantum behavior macroscopically, thereby offering the chance for manipulation of quantum states in a measurable way.
In 1962, Josephson proposed that non-dissipating current would flow from one superconductor to another through a thin insulating layer, see B. D. Josephson, Phys. Lett., 1:251, (1962). Since then, the so-called Josephson effect has been verified experimentally and has spawned a number of important applications of superconducting materials. In particular, it has been found that the thin insulating layer originally used by Josephson is an example of a general class of barriers known as weak links. These weak links are interruptions of the translational symmetry of the bulk superconducting material on the same scale as the coherence length of the material. Examples of weak links include the following: grain boundaries, insulating gaps, tunneling junctions, constrictions, and any locations where the amplitude of the order parameter of the superconductor is diminished. The Josephson effect has been generalized to all weak links in a superconductor. Therefore any small interruption of a superconducting material, or an interface of two different superconductors, behaves as a Josephson junction. Avoiding the formation of weak links where Josephson junctions are not intended can make the fabrication of devices based on superconducting components difficult.
Nevertheless, the Josephson junction has found practical application in a device known as a superconducting quantum interference device (SQUID). The current and voltage of a superconducting loop with two small insulating gaps behaves in a previously unexpected way that depends on the magnetic flux enclosed in the loop. SQUIDs are useful for sensitive measurement and in the creation of magnetic fields. For example, see chapter 1 of A. Barone and G. Paternò, Physics and Applications of the Josephson Effect, John Wiley and Sons, New York, (1982), which is incorporated herein by reference.
Two types of superconductors are regularly used nowadays: conventional superconductors and unconventional superconductors. The most important phenomenological difference between the unconventional superconductors and conventional superconductors is in the orbital symmetry of the superconducting order parameter. In the unconventional superconductors, the pair potential changes sign depending on the direction of motion in momentum space. This has now been experimentally confirmed; see e.g., C. C. Tsuei and J. R. Kirtley, Rev. Mod. Phys., 72, 969, (2000). The effects of this pairing were understood long before this experimental confirmation.
For example, it was discovered that in unconventional superconducting materials such as YBa2Cu3Ox (xe2x80x9cYBCOxe2x80x9d) that have orthorhombic crystal structures, there existed a significant subdominant order parameter mode that is spherical in momentum space (referred to as an s-wave); see K. A. Kouznetsov et al., Phys. Rev. Lett., 79, 3050, (1997).
The coherence length of an unconventional superconductor is not isotropic. In an orthorhombic superconductor, the coherence length in the c-axis direction is much less than in the a and b directions. Correspondingly, the critical current is much smaller in the c-axis direction. Furthermore, the coherence length in all directions of an unconventional superconductor is small enough for a weak link to form easily at any junction. Given that the Josephson effect is present in all weak links, the short coherence length poses a difficulty for forming devices that utilize unconventional superconducting materials.
Hence, superconducting single electron transistors (SET""s) have generally been made from conventional superconductors. Efforts to make them from unconventional superconducting materials have not been particularly successful. See, e.g., S. E. Kubatkin et al., JETP Lett., 63, 126-132, (1996) and A. Tzalenchuk, poster presentation at SQUID 2001, both of which are incorporated herein by reference. The oscillations of a SET made from an unconventional superconducting material would have only a single charge periodicity, not both a single and a double charge period. Both effects are useful in superconducting quantum computing, where a mechanism for controllable switching of supercurrent is important and where the supercurrent charge carriers are Cooper pairs. Thus there is a need for a controllable supercurrent switch that is based on an unconventional superconductor.
Other types of junctions are known, but suffer from deficiencies that prevent their use in superconducting quantum computing. For example, Racah et al., Physica C, 263, 218-224, (1996), incorporated herein by reference, teach a junction comprising: YBCO, aluminum oxide and silver, i.e., an unconventional superconductor and a normal metal, separated by an insulator. However, no Josephson effect (in which Cooper pairs tunnel) was observed in Racah et al.""s structures; instead only quasi-particle tunneling was found. Furthermore such a junction has a dimension on the order of tens of microns.
Furthermore, junctions known in the art are far larger in area than the mesoscopic devices to which they need to be attached. This is a severe limitation, as size is often an enabling feature in quantum computers built from superconducting material. Certain components must be mesoscopic. Therefore, to implement quantum computing structures, Josephson junctions between conventional and unconventional superconductors are necessary, and no junction in the prior art suffices.
In accordance with the present invention, a Josephson junction is presented. In some embodiments, the junction includes an unconventional superconductor, an intermediate material, and a conventional superconducting material. In some embodiments, the resulting junction is in the c-axis direction of an orthorhombic unconventional superconductor. Alternatively, the junction may be oriented so that supercurrent flows in a direction in the a-b plane. The junction may be oriented so that either the c-axis direction or a direction in the a-b plane are aligned with the rest of the junction.
The present invention involves a Josephson junction comprising, in sequence: a first superconducting material layer; an intermediate layer having a first area of overlap with the first superconducting material layer; and a second superconducting material layer having a second area of overlap with the intermediate layer; wherein an area of intersection of the first area of overlap and the second area of overlap is less than or equal to about 0.1 xcexcm2, and wherein the first superconducting material layer is in contact with a substrate. In a preferred embodiment, the first superconducting material is a crystalline material having a crystal structure with an a-axis, a b-axis, and a c-axis; such that the c-axis is normal to the substrate.
A Josephson junction according to the present invention may also be a ramp-type junction wherein a first surface of the first superconducting material is parallel with the substrate; and a second surface of the first superconducting material makes an angle of inclination of between 0xc2x0 and 90xc2x0 with a plane that is normal to the first surface, wherein the angle of inclination is measured in a sense exterior to said first superconducting material and wherein the first surface and the second surface share an edge.
The present invention also involves a superconducting structure comprising, in sequence: a substrate; a first superconducting material layer comprised of unconventional superconducting material and includes a first region and a second region wherein the first region is disjoint from the second region; an intermediate material layer; and a second superconducting material layer that includes an island, wherein the island has a first area of overlap with the first region and a second area of overlap with the second region of the first superconducting material layer; and wherein an electrode is capacitively coupled to the island so that supercurrent can flow coherently between the first region and the second region of the first superconducting material layer.
Josephson junctions according to embodiments of the present invention may be used in superconducting low inductance qubits (SLIQs) and in permanent readout superconducting qubits (PRSQs). They can form the basis of quantum registers, and can allow for parity keys or other devices made from conventional superconducting material to be efficiently coupled to qubits made from unconventional superconducting material. Further, embodiments of the invention may be applicable to any electronic device that utilizes a superconducting junction wherein coherent transport between unconventional superconductors is useful.
In some embodiments, an unconventional superconductor having non-zero angular momentum pairing is placed with its c-axis perpendicular to the substrate. A conventional superconductor having a dominant mode that has zero angular momentum pairing is placed above the unconventional superconductor. Another material such as a normal metal or an insulator separates the conventional and unconventional superconductors to form a heterostructure (or heterojunction) to which electrodes may be attached.
Multiple methods of fabrication are described. Relative sizes of physical parameters needed for operation are introduced. Different materials as intermediate layers are described. The usage of various embodiments of heterojunctions in quantum computing structures is outlined.

Trilayer heterostructure Josephson junctions


Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is disclosed that includes: a data detector circuit, a data decoder circuit, and a multi-path circuit. The data detector circuit is operable to apply a data detection algorithm to a data input and a decoder output to yield a detected output. The data decoder circuit is operable to apply a decoding algorithm to a decoder input to yield the decoder output and a status input. The multi-path circuit is operable to provide the decoder input based at least in part on the detected output and the status input.

The present inventions are related to systems and methods for data processing.
Various data transfer systems have been developed including storage systems, cellular telephone systems, radio transmission systems. In each of the systems data is transferred from a sender to a receiver via some medium. For example, in a storage system, data is sent from a sender (i.e., a write function) to a receiver (i.e., a read function) via a storage medium. The effectiveness of any transfer is impacted by noise, data errors and other issues arising in the data transfer. Turning to FIG. 1, a data processing circuit 100 is shown that includes a data detector circuit 130, an adder circuit 140 and a data decoder circuit 150. A data input 101 is received by data detector circuit 130 along with a data output 152 from data decoder circuit 150, and a resulting detected output 132 is provided to adder circuit 140. Adder circuit 140 subtracts data output 152 from detected output 132 to yield a decoder input 142. Decoder circuit 140 processes decoder input 140 to yield data output 152. In some cases, processing a data input may require many iterations through the combination of data detector circuit 130 and data decoder circuit 150 to recover an original data set. In various cases an insufficient number of iterations may be available rendering recovery of the original data set impossible.
Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for data processing.

Systems and methods for selective decoder input data processing


A method for learning a foreign language using a learning aid is provided. The learning aid includes a reading manual having a plurality of pages organized into a number of sections which are read in an orderly fashion in order to facilitate incremental advancement and masterfulness concerning the learning of a target language. The method involves building an active foreign language alphabet and language as it is done naturally in user's native language. The learning aid further includes an interactive-based, task-oriented system integrated into software for upload onto a computer.

1. Field of the Invention
The present invention relates generally to foreign language learning methods and, more particularly, to a method for learning a foreign language using a learning aid.
2. Description of the Related Art
Any program of learning by its very nature requires teaching, either by one's experience or by formal instruction. The process of teaching follows an interaction with anything that exists, and learning a relationship thereto.
To know or to discover and to identify anything that exists creates cognition, which is the act of knowing or identifying. Cognition may be called perception, according to each individuals' mode of learning (their modality). The task-oriented result is education.
A modification of individual behavior is education. It does not matter whether an individual is learning to tie shoelaces, to housebreak a dog, to resolve complex mathematical equations, or to develop a marketing campaign for canned chicken soup, education occurs when prior learning enables the modification to be achieved. However, achievement is based upon the elements of education functioning within two concepts, intelligence and/or intellect.
All humans exhibit intelligence, which may be defined as memory or recall. It is through experience that individuals proceed from conscious memory or recall to an imprinted action that requires no conscious effort. The experience of learning how to tie shoelaces or open or close a water faucet initially requires conscious memory/recall, but after repetitive actions a modification of behavior takes place and a stimulus to an individual will create a rote response, called imprinting. This basic element of education makes it possible for an individual to touch, type, play a piano, drive a car, or to read, write, and speak words that transmit thoughts.
All humans exhibit intellect in varying degrees, which is the ability to understand relationships. Intellect is the ability to take elements of intelligence and understand their relationship in order to produce reason, as an outcome of learning. This element of education is evidenced by a modification of behavior that may be called understanding or comprehension, and permits the individual to solve highly complex problems.
Everyone uses convergent thinking in order to do daily tasks, whether making breakfast, dressing, or going to the supermarket, intelligence permits routines to easily be accomplished. Repetitive tasks are more easily accomplished through convergent thinking operations. The degree to which individuals are convergent in their thinking is generally environmentally generated. Convergent thinkers tend to be very literal in their understandings of concepts, and especially new concepts. They tend to associate themselves with rigid and unyielding attitudes and policies regarding nation, political party, culture, organization, or a belief system in which they have been imprinted. The degree to which this behavioral mode impacts their education is a function of an individual's behavior modification. For convergent thinkers, utilizing a high-interest level material, which delivers immediate gratification where such material is transmitted through imprinting in one's native tongue and transmuted to a target language, can be a major driving force concerning motivation for implementing a method for learning a foreign language. Convergent thinkers rely heavily upon their intelligence (memory/recall). To the convergent thinker, a brick may be used to build a house, build a fireplace, construct a brick walkway, or to build a wall.
Environment plays a major role in creating divergent thinking skills. The ability to consider divergent understandings of learning anything is called intellect. Knowing or identifying anything is cognition, and once it is registered in the individual's memory, it may be re-cognated or recognized. Combinations of previously learned material are brought together by the divergent thinker in order to provide reasoned understandings of new concepts. These new concepts come together in a confluent amalgam to produce education, a new understanding that has modified the individual's behavior. Divergent thinkers rely heavily upon their intellect, the ability to see relationships. To the divergent thinker, a brick may be ground into red powder and mixed with plaster in order to make a relief map of the Rocky Mountains. Two bricks may be placed in a lavatory's reservoir to reduce water consumption. The inside of a brick may be hollowed and filled with jewelry for placement in a brick wall to hinder burglars.
Learning is completely dependent upon the individual's modalities during the act of cognition. A brief examination of some of the modalities of learning, and its impact upon the modification of the learner's behavior is imperative if education is to take place. Convergent and divergent thinking operations are performed by individuals using their favorite combination of methods for solving problems, because their experience has shown them that the mindset of methods they are using to think has been the most productive manner to learn anything they consider. Those methods of solving problems are called modalities.
Auditory discrimination is vital if the individual is to pursue language in a meaningful way. Primary to the effective use of a method for learning a foreign language, an understanding of the sounds of printed letters as they are blended together into a word which is identifiable as a component of an idea. This concept is referred to as codex. English language learners follow a phonetic approach, which is based on convergent thinking. These learners quickly move from decoding letters into sound, to whole word recognition in order to form word clusters that can be put together with lucidity. In the Anglo-Saxon language, sounds of the word are often different than the sounds in the word. The word "sugar" is not "soogar". The visual discrimination of gum/gun, when expressed in the context of a sentence, is often difficult if auditory discrimination has not be properly dealt with, as auditory discrimination proceeds visual discrimination in human development. For example, "He took the gum/gun in his hand," requires the use of divergent thinking abilities as the reader adjusts the literal decoding of the word as perceived and discriminates its meaning as evidence by the word's proper pronunciation because the reader is aware of the sense of the sentence. For example, "You can open the can." This visual discrimination follows perceptions/cognition and is completely dependent upon auditory discrimination.
The ability to read a map, follow a blueprint, understand a design, navigate a course, and conceive geometric concepts is the result of a schematic modality which has very important implications for learning. Many people have learned to read using flash cards which enable individuals to wee whole words that they might have difficulty spelling, such as Lieutenant, cafeteria, Mississippi, and boulevard. However, these words are readily understood in the context of a sentence thanks to schematic ability on the part of the reader. Schematic thinking occurs when the imprinting of the word's design is established in a convergent inventory of knowledge and it is this cognition that permits recognition of a word that represents identifiable thought. A common example is the Coca-Cola® logo.
Language learning for individuals with a strong figural modality can be strengthened using imprinting as an outcome of convergent thinking. The symbiotic relationship of mathematics to musical ability, which is often used in the playing of an instrument with both hands, requires the functional understanding of an equation. The popularity of Dr. Seuss's® basic use of poetical music in a series of children's books to young children, below the age of puberty, when a better understanding of relationships provokes intellectual thinking, gives testimony to the subliminal use of the music in our language and its importance in imprinting whole words, word clusters, and/or a codex in an individual's inventory of knowledge as a result of convergent thinking operations. Childish jingles, advertising slogans, popular tunes, the Psalms, and worship liturgics are understood and retained through the modality of figural thinking operations.
It is most often thought that there is a symbiotic relationship between age and maturity, and that is the reason children and adolescents tend to have a short attention span. That concept is false. Children and adolescents can absorb themselves in a video game or an age appropriate television show for hours at a time. Adults, at any age, evidence a very short attention span except for one intervening variable, their apperceptive base. Apperception is the ability to perceive clearly, to observe, to recognize and to have full understanding of the assimilation of new information as a result of convergent thinking (memory/recall) operations provoking the individual's inventory of knowledge, which may produce, in the case of a divergent thinker, intellectual outcomes. An expanded attention span fuels the desire not to leave in the middle of a movie, television show, interesting book or other sedentary intellectual involvement. An expanded attention span is often identified as motivation. It relies heavily upon an apperceptive base which motivates the individual's desire for an outcome concerning the current task-oriented activity. That outcome has been projected by the individual's prior inventory of knowledge. The motivating result is satisfaction, because the individual projected the end of the movie, the television show, the interesting book, or other activity. A method for learning a foreign language must provide high interest level, age-appropriate material, synchronized with a program which provides audio and visual discrimination and its concomitant delivery of a phoneme inventory to the learner.
In teaching a foreign language, many traditional methods have been utilized such as the translation method, the audio-lingual method, the direct method, and the total immersion method. These methods utilize memorization, grammar, repetition, speaking and listening, communication exchange, learning aids, and audio-visual media. However, the aforementioned conventional methods have been unsuccessful in providing a method by which a foreign language can be learned quickly, easily, and efficiently.
Accordingly, there is a widely recognized need for a method by which a foreign language can be learned by building an active foreign language alphabet in a natural way as it is done in user's native language in a manner which is quick, easy, and efficient. The development of the method for learning a foreign language fulfills this need.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention; however, the following references were considered related:
U.S. Pat. No. 6,325,630 B1, issued in the name of Grabmayr;
U.S. Pat. No. 4,734,036, issued in the name of Kasha;
U.S. Pat. No. 5,735,693, issued in the name of Groiss;
U.S. Pat. No. 5,810,598, issued in the name of Wakamoto;
U.S. Pat. No. 6,341,958 B1, issued in the name of Zilberman;
U.S. Pat. No. 6,409,510 B1, issued in the name of Firebaugh;
U.S. Pat. No. 6,736,641 B2, issued in the name of Quiroz;
U.S. Pat. No. 5,215,466, issued in the name of Rubio;
U.S. Pat. No. 3,271,884, issued in the name of Roberson;
U.S. Patent Application no. 2003/0203343 A1, published in the name of Milner;
U.S. Pat. No. 5,275,569, issued in the name of Watkins; and
U.S. Pat. No. 6,810,374 B2, issued in the name of Kang.
Consequently, a need has been felt for an improved method for learning a foreign language in a manner which is quick, easy, and efficient.

Apparatus and system for learning a foreign language


The method of the invention estimates a total processing cost incident to execution of a query statement in respect of a relational database, wherein execution of the query statement results in a further execution of a trigger procedure. The method first estimates the query statement's costs by analyzing components of the query statement to determine a processing time there for in relation to a database table that is the target of the query statement. The method then determines the number of rows that are affected in the database table as a result of execution of the query statement. Next, components of a trigger procedure that is invoked in response to execution of the query statement are analyzed to determine a "base cost" for a single execution of the trigger procedure visa-vis data that is contained in a single row of the database table. The components of the trigger procedure are next analyzed to determine a per row cost for execution of the trigger procedure. The per row cost is determined from an estimate of time required for execution of the trigger procedure for a single row and from an estimate of time required for execution of the trigger procedure for a plurality of rows. Thereafter, the total processing cost of a query statement is calculated by adding the query statement cost to a sum of the either (i) the base cost if only one row is subjected to the query statement or (ii) the per row cost, multiplied by the number of rows affected by the query statement.

As is well known, database queries are often posed in a non-procedural language such as "Standard Query Language" or SQL. Queries dispatched to relational databases include the following four actions: select, insert, update and delete. Such queries are used to interrogate and modify logical tables, arranged in rows and columns, in the relational databases. A query which is dispatched to a database interrogates a selected table(s) and, depending upon the syntax of the query, returns from none to many rows of the interrogated table(s) which fit the query condition and/or action.
Query optimizer functions are performed by relational database management systems and enable a choice to be made from among a plurality of query strategies so as to arrive at an efficiently executable plan. The computational complexity of the optimization process and the resulting execution efficiency of the plan chosen are dependent upon the number of possible primitive operator sequences that must be evaluated by the optimizer. U.S. Pat. No. 5,301,317 to Lohman et al., assigned to the same Assignee as this application, describes a system for automatic adjustment of resources devoted to query optimization, according to an estimated query execution time. The Lohman et al. system permits a query optimizer to automatically trade off the time spent estimating the execution cost of alternate query execution plans against the potential savings and execution time that one of those alternate plans may yield.
An aspect of query optimization is the resulting execution cost of the query in terms of utilized central processing unit (CPU) time, input/output (I/O) time, and minimum elapsed time that is required by execution of the query statement. An optimizer generally chooses the query plan which results in the least cost to accomplish the execution of the query statement.
U.S. Pat. No. 5,734,884 to Eberhard et al., assigned to the same Assignee as this Application, describes a software tool for estimating the costs of a program which accesses a relational database. The costs may include execution costs of the application or of a transaction, an SQL statement and/or a utility. Execution costs include CPU time, I/O time and minimum elapsed time, wherein minimum elapsed time is an estimation of the amount of time that the application, transaction, SQL or utility will take to execute. The execution costs may also reflect system performance effected by transactional accessing of the database, including batch processing. For estimating the execution costs of a transaction, the software tool generates a simplified transaction definition, including a simplified query statement definition, and a frequency of execution of the query statement in the transaction. The software tool then generates an estimated execution cost based upon the syntax of the simplified query statement and the frequency of execution thereof. The disclosure of both U.S. Pat. Nos. 5,301,317 and 5,734,884 are incorporated herein by reference.
As above indicated, a query statement causes dispatch of a select, insert, update or delete command to one or more tables in a relational database. In response, from 0 to N rows are returned which conform to the condition expressed in the query statement. If the returned data meets the terms of a condition that is associated with the query, a "trigger" procedure is or may be invoked.
A trigger procedure is a responsive program which is automatically executed in response to data, returned (in response to a dispatched query) which meets a condition associated with the trigger procedure. A trigger procedure may be executed in response to each row that is affected by the query or may be executed once for all rows that are affected. A simple example of a query is as follows. Assume that an SQL query statement requires the insertion of an employee name into a specified department that is listed in a database table. Assume further that the user neglects to enter the department number in the SQL query statement. Upon dispatch of the SQL query statement, the database management program causes a trigger procedure to be executed to cause display of a message to the user to enter a department number in the SQL statement.
Trigger procedures can be quite complex and may be dependent upon a number of conditions being met before they execute. Llirbat et al. in "Eliminating Costly Redundant Computations from SQL Trigger Executions", Proceedings of the 1997 ACM Sigmod, Tucson, Ariz. May 13-15, 1997, pp. 428-439, describe a procedure which attempts to eliminate repeated calculations which result from certain types of SQL triggers, to reduce the processing cost thereof. More specifically, Llirbat et al. eliminate redundant computations of SQL triggers when they are costly. Invariant sub-queries are extracted from trigger conditions and actions and the most "profitable" invariants are memorized and utilized in a re-write of the SQL triggers.
As indicated above, a trigger may be caused to execute for each row of a table returned in response to an SQL query statement or may be caused to execute once per SQL query statement, irrespective of the number of rows returned in response to the SQL query statement. It is known, however, that the execution cost of a trigger may not be a linear function based upon the number of rows that are returned. Notwithstanding the potential complexity of estimating trigger costs, there is still a need, during the optimization process, to arrive at an estimate of trigger cost to enable a realistic view of the actual cost of the execution of an SQL query statement and the one or more resulting triggers which occur as a result of the execution thereof.

Data base optimization method for estimating query and trigger procedure costs

International Business Machines Corporation


An object sharing system and an object sharing method are provided. The system includes a plurality of shared objects and a plurality of data servers. The shared objects are respectively provided by a plurality of object suppliers. The data servers are respectively provided by the object suppliers and connected to form a distributed data redundancy network so as to store a plurality of sub-secret data separated from shared secret information in a decentralized way. The data server of each of the object suppliers is connected to the shared objects provided by the object supplier, and collects a required quantity of sub-secret data for reconstructing the shared secret information via the distributed data redundancy network so as to reconstruct the shared secret information configured to verify an access right to the shared object for a user device when receiving an access request for the shared object from the user device.

With recent advance in technology, the network has become an indispensable source for obtaining information to people nowadays. However, as more and more technologies are developed based on networks, information security becomes one of the most significant issues to be discussed.
Most of the current networks at this stage adopt use of a centralized architecture which uses a central arbiter to determine facts and assess the accuracy of the recorded data. However, due to the low level of trust between vendors and the doubts about interoperability of the centralized architecture, managers of the centralized architecture are unable to self-certify when there is a dispute. As a result, such information security exchange is questioned and the cost of building trust is so high that another new information isolated island is formed and a shared spirit is hard to achieve.
Furthermore, since the centralized architecture aggregates data from multiple sources to a single node, once being attacked, there is a risk of a single node failure or a data leakage. In addition, since the accuracy of the data is only maintained unilaterally, it is very difficult to discover data tampering on a part of the data or the data at a specific time point without a proper confirmation mechanism.

Object sharing system and object sharing method

Industrial Technology Research Institute


A self-refresh module includes an oscillator configured to provide a first signal having a first frequency, a trimming divider configured to trim the first signal to provide a second signal having a second frequency, and a temperature sensor configured to sense a temperature of the memory device and provide a temperature signal. The self-refresh module includes a temperature look-up table configured to receive the temperature signal and provide a third signal based on the temperature signal, and a temperature divider configured to provide a self-refresh pulse signal based on the second signal and the third signal.

Memory speed and memory capacity continue to increase to meet the demands of system applications. Some of these system applications include mobile electronic systems that have limited space and limited power resources. In mobile applications, such as cellular telephones and personal digital assistants (PDAs), memory cell density and power consumption are issues for future generations.
To address these issues, the industry is developing random access memories (RAMs) for mobile applications. One type of RAM, referred to as CellularRAM, is a high performance and low power memory designed to meet the growing memory density and bandwidth demands of future designs. CellularRAM is a pseudo static RAM (PSRAM) that offers a lower cost per bit ratio than typical solutions. Also, CellularRAM offers static random access memory (SRAM) pin and function compatibility, external refresh-free operation, and a low power design. CellularRAM devices are drop-in replacements for most asynchronous low power SRAMs currently used in mobile applications, such as cellular telephones.
Each memory cell in a DRAM includes a transistor and a capacitor. The capacitor is charged and discharged to represent a logic "0" or a logic "1". During a read operation, a data bit value stored on the capacitor is read. During a write operation, a data bit value is written to the capacitor. A read operation on a memory cell is destructive. After each read operation, the capacitor is recharged or discharged to the data value that was just read. In addition, even without read operations, the charge on the capacitor discharges over time.
To retain a stored data bit value, the memory cell is refreshed periodically by reading and/or writing to the memory cell. All memory cells within a DRAM are periodically refreshed to maintain their values. During self-refresh, the rate at which the memory cells are refreshed is typically defined by a self-refresh module including a self-refresh oscillator and trimming circuits. The self-refresh oscillator and trimming circuits typically provide a self-refresh pulse for initiating a self-refresh of the memory cells. The base frequency of the self-refresh oscillator contributes to standby power consumption. Therefore, by reducing the oscillator base frequency of the self-refresh oscillator, the standby power consumption can be reduced.

Temperature dependent self-refresh module for a memory device


A system and method are provided for determining ink jet printing system parameters by selecting an appropriate linearizing transformation for application to images to be printed on a printing system for a specific substrate. These transformations can be any transformation capable of being applied in graduated increments and having a corresponding incremental visual influence on the printed output. The present invention allows the user to determine multiple parameters for the printer, including for example, tone scale correction, determination of upper ink limits, amount of under color removal, and allows the user to identify the proper ink level for optimum quality of graphics and/or text printing.

Various techniques are known for digital printers to provide continuous tone (monochrome or color) printing. Traditional offset printing systems compensate for tone nonlinearity through the measurement of dot gain. Dot gain is the percentage of spot size increase of a 50% intensity dot. This dot gain is corrected in the production of the printing plates. Further correction can be done through adjustment of the pressure between the transfer media and the printing plate. The object is to obtain a linear tone scale from the lightest to the darkest shade of a given ink in the printing system.
High speed digital ink jet printing systems apply the ink directly to the substrate as directed by the input data. In certain digital printing systems the application of a linear gradation of ink to a substrate does not result in the appearance of a linear gradation in tone. The image data must be corrected so that tone linearity can be achieved on a particular substrate. In the past, it has been necessary to print and measure the resulting tone from samples of a number of printed ink levels in order to determine the appropriate data transformation. This transformation was then applied to the image data.
Typically, printing system configurations and substrates differ in acceptable maximum ink limit. Problems in image quality, such as edged definition and loss of detail in the shadow areas, can result. Image quality and ink drying time varies significantly with the substrate As conditions of the printing system and substrate type change regularly, it is often necessary to determine new data transformations that redefine the tone curve shape and upper ink limit for each ink in the system.
It would be desirable to be able to determine an appropriate transformation for application to images to be printed on the given system and substrate.

Digital image optimization incorporating paper evaluation


A thermal transfer-type label printer and an optical disc apparatus are integrated to miniaturize a multi-function label printing apparatus. An information recording/reproducing unit that carries out recording or reproduction of information on a recording surface of an optical disc is incorporated within a disc tray unit of a label printing apparatus that presses a thermal transfer film ribbon, on which printing information has been formed, onto a label surface of an optical disc mounted on a disc mounting part of the disc tray unit, and transfers the printing information onto the label surface using a heat roller. The recording or reproduction of information on the recording surface of the optical disc and the transferring of the printing information on the label surface of the optical disc are carried out on the disc tray unit. When transferring the printing information, the clamping of the optical disc by a disc clamper is released and a turntable and the disc clamper are withdrawn to a non-clamping position.

1. Field of the Invention
The present invention relates to a label printing apparatus that records or reproduces information on an optical disc such as a CD (Compact Disc) or DVD (Digital Versatile Disc) and also prints information on a label surface of the optical disc.
2. Description of the Related Art
In recent years, the spread of optical discs such as CD-R/RW and DVD-R/RW/RAM has been accompanied with increasing demand for a label printer that can print images and/or character information, which has been generated on a personal computer or the like, on the label surface (upper surface) of a user-made CD or DVD. Also, multi-function label printing apparatuses, where an optical disc apparatus that records information on an optical disc and the label printer mentioned above are combined and enclosed within a single housing, have also entered the market.
As shown in FIG. 1 to FIG. 3, in one example of a multi-function label printing apparatus, optical disc apparatuses 102, 103 that record information on a recording surface (the lower surface) of an optical disc, a label printer that prints information such as images and an index onto a label surface (the upper surface) of an optical disc, and a disc conveying mechanism 120 that conveys optical discs are internally provided within a housing 101. In addition, a power supply circuit 130 that supplies power to the optical disc apparatuses 102, 103, the label printer 104, and the disc conveying mechanism 120 and a control circuit 131 that controls the optical disc apparatuses 102, 103, the label printer 104, and the disc conveying mechanism 120 are provided inside the housing 101.
The optical disc apparatuses 102, 103 are composed of CD-R/RW drives or DVD-R/RW/RAM drives or the like that record information by irradiating the recording surface of an optical disc with laser light, and on front surfaces thereof include disc trays 105, 106 on which an optical disc is mounted. The disc trays 105, 106 are provided so as to slide between a changing position where discs are changed and a loading position where the recording of information is carried out.
The label printer 104 also has a disc tray 107 on which an optical disc is mounted. The disc tray 107 is provided so as to slide between a changing position where discs are changed and a printing position where the printing of information is carried out. The label printer 104 is constructed so as to be open to above when the disc tray 107 has moved to the printing position, with an ink cartridge 108 moving in a left-right direction above the disc tray 107. Ink is sprayed from a head 110 of the ink cartridge 108 that moves in a left-right direction along a traveling rail 109 suspended above and across the disc tray 107 onto the label surface of the optical disc to print desired information. It should be noted that in the label printer 104, the sliding stop position of the disc tray 107 is moved in small steps so that printing can be carried out in the entire region of the label surface of an optical disc.
The disc conveying mechanism 120 includes a guide rail 121 that is suspended between a first disc storage part 111 where unrecorded optical discs are stored and a second disc storage part 112 where recorded optical discs are stored, a grabbing part 122 that moves horizontally in the left-right direction along the guide rail 121, and a clamper 123 that is supported on the grabbing part 122. The grabbing part 122 has a raising/lowering mechanism 124 with a pantograph construction in which first and second arms composed of a pair of parallel links are combined, and is constructed so as to raise and lower the clamper 123 and to insert the clamper 123 into a center hole of an optical disc to clamp the optical disc. With the disc conveying mechanism 120 of this construction, an optical disc is conveyed between the first disc storage part 111, the optical disc apparatuses 102, 103, the label printer 104, and the second disc storage part 112.
The multi-function label printing apparatus 100 is a recording/printing apparatus that automatically carries out a recording process that records information to be stored on an optical disc according to instructions from a host computer (not shown), a printing process that prints information such as images and an index on the label surface of the optical disc, and a disc conveying process that conveys discs between the first disc storage part 111 and the second disc storage part 112, so that compared to a system in which an optical disc apparatus and a label printer that are separately constructed are respectively connected to a host computer, there are the effects that the burden of manually changing discs is eliminated and the operating efficiency is increased. However, although optical disc apparatuses and a label printer are enclosed within the same housing in the multi-function label printing apparatus 100, the optical disc apparatuses and label printer are separate devices, so that there is the problem that the multi-function label printing apparatus is large. There is also the problem that the optical disc changing process is complex, which leads to increases in cost.
To solve the above problems, information recording apparatuses for optical discs have been proposed (see, for example, Patent Documents 1 to 4) where an optical disc apparatus and a label printer are integrated and the recording of information on the recording surface and the printing of information on the label surface can be carried out on a shared turntable.
Patent Documents 1 and 2 mentioned above disclose a label printing apparatus for discs and an information recording apparatus for optical discs including a spindle motor that rotates an optical disc at a predetermined speed, a pickup that records recording information and is disposed facing the recording surface of the optical disc, and an ink jet apparatus that is disposed facing the label surface of the optical disc and prints printing information, where recording information is recorded and printing information is printed while an optical disc is rotated at a predetermined speed.
Patent Document 3 mentioned above discloses an optical disc drive apparatus internally equipped with a label printer. The apparatus includes a spindle motor that holds and axially rotates an optical disc, a data head that is provided facing a data recording surface and records and reproduces data on the optical disc, a data head driving mechanism that moves the data head back and forth in the radial direction of the optical disc, a label printing head that is provided so as to face the label surface, and a printing head driving mechanism that moves the label printing head back and forth in the radial direction of the optical disc. The apparatus records data on the data recording surface and simultaneously prints a label on the label surface in synchronization with the rotation of the optical disc.
Patent Document 4 mentioned above discloses a recording apparatus including a rotation tray unit on which a disc medium, which is a rotating recording medium, is placed, a rotation tray control unit that controls the tray, a writing means (optical pickup) that writes data on the disc medium, and a recording means (recording head) that records on a disc medium surface (the label surface). The recording apparatus carries out the writing of data and the recording of the disc label in synchronization with the rotation of the disc medium.
[Patent Document 1]
Japanese Laid-Open Patent Application No. H05-238005
[Patent Document 2]
Japanese Laid-Open Patent Application No. H06-31906
[Patent Document 3]
Japanese Laid-Open Patent Application No. 2001-291235
[Patent Document 4]
Japanese Laid-Open Patent Application No. 2003-257153
The apparatuses disclosed by Patent Documents 1 to 4 listed above are alike in that an optical disc is placed on a turntable and the recording of information and the printing of the label surface are carried out while rotating the optical disc and in that the label printer uses an ink jet printing method. Label printers can be broadly classified into two types, ink jet types and thermal transfer types. Ink jet printing is a method where printing is carried out by spraying ink onto the label surface of an optical disc using a head, while thermal transfer printing is a method where printing information formed on a transfer sheet is pressed and transferred onto the label surface of an optical disc by a heat roller, and it is thought that the label printers incorporated in the apparatuses of Patent Documents 1 to 4 above all carry out ink jet printing for a particular reason. That is, during ink jet printing, the head that sprays ink does not contact the label surface of the optical disc. During thermal transfer printing, a heat roller is pressed onto the label surface of an optical disc via a transfer sheet, and if the heat roller is pressed on the optical disc in a state where the optical disc is placed on a turntable, that is, in a state where the optical disc has been lifted up from the disc tray, the optical disc will warp, so that it will not be able to transfer the printing information and there is even the risk of the optical disc becoming damaged. On the other hand, with ink jet printing, the head does not contact the optical disc, so that printing information can be easily printed even when the optical disc is attached to a turntable, which means that an ink jet printer is suited to integration with an optical disc apparatus.
However, ink jet printers print by spraying ink onto the label surface of an optical disc, so that if the optical disc is rotated before the sprayed ink has dried, due to centrifugal force the ink on the optical disc can disperse towards the outer periphery of the optical disc or become blurred, so that there is the problem of poor image quality for the printed image. In addition, with apparatuses such as those disclosed in Patent Documents 1 to 4 where the optical disc is rotated and printing is carried out in synchronization with the rotation of the optical disc, there is the problem that ink sprayed from the head is dispersed by wind pressure produced between the label surface of the optical disc and the head, which lowers the quality of the printed image and means that the desired printing information cannot be printed properly. Thermal transfer-type label printers have a further advantage in that it is possible to print the printing information more clearly and more stably than an ink jet-type label printer, and it would be desirable to put this advantage to use.


A feminine hygiene pad with releasable attachment is a conventional feminine hygiene pad having an absorbent upper layer and a liquid impermeable lower layer, at least one elastic element attached to the lower layer to maintain the feminine hygiene pad in a non-collapsed state, and a pair of releasable attachments (fasteners) for releasably securing the lower layer to an inner surface of an undergarment. The pair of releasable attachments are formed from just the hook portions of hook and loop fasteners, and are attached to respective longitudinally opposed ends of the lower layer. The material forming the undergarment, such as cotton or the like, acts as a corresponding loop portion for releasable securement thereto.

1. Field of the Invention
The present invention relates to absorbent articles, and particularly to a feminine hygiene pad with a releasable attachment for releasable securement to undergarments.
2. Description of the Related Art
A feminine hygiene pad (also commonly referred to as a sanitary napkin, sanitary pad or menstrual pad) is an absorbent item worn by a woman while she is menstruating, recovering from vaginal surgery, for lochia (i.e., post-birth bleeding), or any other situation where it is necessary to absorb a flow of blood from a woman's vagina. The feminine hygiene pad is worn externally, between the vulva and a woman's undergarment.
The length, size, and shape of feminine hygiene pads vary greatly, due to a wide variety of uses, body types, undergarment styles and sizes, and personal preference. Other options are often offered in a manufacturer's line of pads, such as wings or tabs that wrap around the sides of the woman's underwear to add additional leak protection and help secure the pad in place. Although absorbency and comfort are primary concerns in the manufacture and use of feminine hygiene pads, the overall stability and stable positioning of the pad is also of great concern.
Due to movement of the body during sleep, exercise, or simply through walking or shifting one's weight, a feminine hygiene pad can shift position within the undergarment, thus decreasing the level and scope of protection of the undergarment from leakage. Further, such movements may also cause the pad, which is typically manufactured to be as lightweight, thin and flexible as possible, to fold, bunch or otherwise deform within the undergarments, thus causing discomfort for the user and further decreasing the scope of protection of the undergarment from leakage. Although the use of adhesives to maintain the position of a pad within the undergarment is known, such adhesive attachments may be difficult for the user to apply to undergarments when time and space are constrained, such as in a public bathroom, and can further damage the undergarment with a sticky adhesive residue. Adhesives are also often not strong enough to maintain the pad in place for extended periods of time, or under the added conditions of body heat and perspiration.
Thus, a static and stable feminine hygiene pad with a releasable attachment, and further with static bands, solving the aforementioned problems is desired.

Static and stable feminine hygiene pad with releasable attachment


A pixel circuit includes a first transistor that supplies a data signal to a first node in response to a scan signal. The pixel circuit may also include a capacitor that is connected between the first node and a ground voltage and a detecting unit that is connected in parallel with the capacitor. More so, the detecting unit may change a voltage of the first node by being activated in response to a mode signal. Also, the detecting unit may have resistance that varies according to an external stimulus. The pixel circuit may also include a second transistor that is complementarily activated with respect to the detecting unit in response to the mode signal, and that provides a voltage of the first node.

1. Field
The present disclosure relates to a pixel circuit, and more particularly, to a pixel circuit capable of detecting and displaying an external stimulus, and a display apparatus including the pixel circuit.
2. Description of the Related Art
An active matrix liquid crystal display (AMLCD) capable of detecting an external stimulus desires or demands use of elements externally added to internal elements or a screen of the AMLCD. In general, a method of operating an AMLCD is a resistive touch method.
However, when the AMLCD capable of detecting the external stimulus is embodied, additional elements for detecting an external stimulus are arranged such that a display apparatus having the AMLCD may not be small-sized.

Pixel circuit and display apparatus including the same


A reflow soldering system comprising one or a plurality of individually heatable soldering process zones. The reflow soldering system is configured to supply heat to a workpiece selectively through condensation or through convection or as a combination of convection and condensation.

The term reflow soldering refers to a soft soldering process for soldering electronic components, which is commonly used in the field of electrical engineering. In the first step of reflow soldering, a soft solder in the form of a soldering paste is applied to a substrate such as a board/circuit board before the latter is populated. In the next step, components are then placed onto the sticky soldering paste. Subsequently, the populated circuit board is heated such that the solder contained in the soldering paste melts.
In order to achieve the best possible results in reflow soldering, a particular temperature-time profile, the so-called "reflow profile", should be determined prior to each process. On the basis of this analysis, the soldering system can be adjusted to the production process as regards process stability and energy consumption. The reflow profile depends on the thermal mass as well as on the material characteristics and the nature of the various components on the circuit board. Without specific reflow profiling, sensitive components may be overheated, damaged or become unstable, and this would lead to a reduction of their function. In addition, the temperature-time profile determines the quality of the solder joints. In order to minimize these deficiencies, it will be advantageous to determine an optimum temperature profile/reflow profile matched to a product to be manufactured.
The heating processes used for this purpose aim at implementing the determined reflow profiling efficiently and accurately. To this end, various heat transfer mechanisms, such as "convection" and "condensation", are used in electronics production for soldering electronic assemblies. Both processes have their advantages and disadvantages, which decide on the use of the respective process.

Reflow soldering system for combined convection soldering and condensation soldering


Described are methods and apparatuses for delivering fistula plugs into fistulae having at least a primary fistula opening, a secondary fistula opening, and a fistula tract extending therebetween. Illustratively, some inventive methods involve delivering a fistula plug into a fistula tract through a primary fistula opening and toward a secondary fistula opening, while others involve delivering a fistula plug into a fistula tract through a secondary fistula opening and toward a primary fistula opening. In certain aspects, a fistula plug is pushed and/or pulled through a fistula tract along a guidewire or other plug-guiding device, potentially protected by a protective delivery device such as a sheath, capsule or other suitable delivery vehicle.

The present invention relates generally to medical devices and in particular aspects to apparatuses and methods for treating fistulae.
As further background, fistulae can occur for a variety of reasons such as but not limited to as a congenital defect, as a result of inflammatory bowel disease such as Chron's disease, irradiation, trauma such as childbirth, or as a side effect from a surgical procedure. Additionally, several different types of fistulae can occur in humans, for example, urethro-vaginal fistulae, vesico-vaginal fistulae, tracheo-esophageal fistulae, gastrointestinal fistulae including but not limited to gastrocutaneous, enterocutaneous and colocutaneous fistulae, and any number of anorectal fistulae such as recto-vaginal fistula, recto-vesical fistulae, recto-urethral fistulae, and recto-prostatic fistulae.
A gastrointestinal fistula is an abnormal passage that leaks contents of the stomach or the intestine (small or large bowel) to other organs, usually other parts of the intestine or the skin. For example, gastrojejunocolic fistulae include both enterocutaneous fistulae (those occurring between the skin surface and the intestine, namely the duodenum, the jejunum, and the ileum) and gastric fistulae (those occurring between the stomach and skin surface). Another type of fistula occurring in the gastrointestinal tract is an enteroenteral fistula, which refers to a fistula occurring between two parts of the intestine. Gastrointestinal fistulae can result in malnutrition and dehydration depending on their location in the gastrointestinal tract. They can also be a source of skin problems and infection. The majority of these types of fistulae are the result of surgery (e.g., bowel surgery), although sometimes they can develop spontaneously or from trauma, especially penetrating traumas such as stab wounds or gunshot wounds. Inflammatory processes, such as infection or inflammatory bowel disease (Crohn's disease), may also cause gastrointestinal fistulae. In fact, Crohn's disease is the most common primary bowel disease leading to enterocutaneous fistulae, and surgical treatment may be difficult because additional enterocutaneous fistulae develop in many of these patients postoperatively.
The path which fistulae take, and their complexity, can vary. A fistula may take a take a "straight line" path from a primary opening to a secondary opening, known as a simple fistula. Alternatively, a fistula may comprise multiple tracts ramifying from a primary opening and have multiple secondary openings. This is known as a complex fistula.
Current treatment options for gastrointestinal fistulae vary. Depending on the clinical situation, patients may receive IV nutrition and go a period of time without food to try to get the fistula to close on its own. Indeed, nonsurgical therapy may allow spontaneous closure of the fistula, although this can be expected less than 30% of the time according to one estimate. A variable amount of time to allow spontaneous closure of fistulae has been recommended, ranging from 30 days to 6 to 8 weeks. During this time, external control of the fistula drainage can prevent skin disruption and provide a guideline for fluid and electrolyte replacement. In some cases, surgery is necessary to remove the segment of intestine involved in a non-healing fistula.
When surgery is deemed necessary, one operation for fistula closure is resection of the fistula-bearing segment and primary end-to-end anastamosis. The anastomosis may be reinforced by greater omentum or a serosal patch from adjacent small bowel. Still other methods for treating fistulae involve injecting sclerosant or sealant (e.g., collagen or fibrin glue) into the tract of the fistula to block the fistula. Closure of a fistula using a sealant is typically performed as a two-stage procedure, including a first-stage seton placement and injection of the fibrin glue several weeks later. This allows residual infection to resolve and to allow the fistula tract to "mature" prior to injecting the sealant. If sealant or sclerosant were injected as a one-stage procedure into an "unprepared" or infected fistula, this may cause a flare-up of the infection and even further abscess formation.
There remain needs for improved and/or alternative fistula plugs, as well as apparatuses and methods for delivering fistula plugs into the body. The present invention is addressed to those needs.

Fistula plugs and apparatuses and methods for fistula plug delivery


Steering control system for a vessel including at least two propulsion units pivotally arranged in relation to the hull of the vessel for generating a driving thrust of the vessel in a desired direction, wherein each propulsion unit is moveable within a working volume defined for each propulsion unit and wherein the working volume for neighboring propulsion units of the at least two propulsion units have a common space, the control system including at least two separate control units each controlling an associated propulsion unit, and a steering control instrument for determining the desired angular position of the propulsion units, where each of the separate control units are arranged for receiving a first input signal from the steering control instrument for determining the desired angular position of its associated propulsion unit and second input signal(s) originating from the other separate control units, associated with neighboring propulsion units, which second input signal(s) indicating the status of the their associated propulsion units.

The present invention relates to a steering control system. The invention particularly relates to a steering control system for a vessel including a plurality of propulsion units which are pivotally arranged in relation to the hull of the vessel in order to generate a driving thrust in a desired direction. The invention furthermore relates to a vessel including such a steering control system and a method for controlling a steering system of a vessel.
Vessels having a plurality of pivotally arranged propulsion units are widely known in the art. The position of the propulsion unit in relation to the hull of the vessel determines the direction of a driving thrust and thus steers the vessel in a desired direction. Pivotally arranged propulsion units of different types are known, such as for instance out board engines arranged in the stem of the vessel, out board drive units pivotally arranged in relation to the hull, and which put board drive units are powered from a non rotatably arranged power unit such as for instance of the type described in WO03093105 and azimuthal drive Units where the propulsion unit together with its power unit are pivotally arranged in relation to the vessel such as of the type described in U.S. Pat. No. 6,688,927. Small and middle size vessels, that is vessels having a length from 5-25 meters, frequently include a plurality of propulsion units for driving the vessel. These propulsion units are normally mechanically linked to each other in order to ensure safe steering of the propulsion units. An example of such a: conventional mechanically linked set of propulsion units is shown in FIG. 1. The steering control is normally performed by a single mechanical or hydraulical steering system physically connecting the propulsion unit with a steering wheel. With this type of steering system it is ensured that all propulsion units assume the same angular position relative to the hull. The latest development in steering systems for vessels have introduced steer by wire systems for small and middle sized vessels. In steer by wire system a steering control instrument, for instance a steering wheel or a joystick, is used for generating control signals which control signals are received by a control unit or units arranged for controlling the position of associated propulsion units, via use of actuators. The use of a steer by wire system enables individual positioning of each individual propulsion unit. By individually controlling the position of the propulsion units it is possible to steer the vessel in more elaborate steering patterns. It is for instance possible to allow the propulsion units to assume a slight "toe-in" position, that is the propulsion units on each side of the centre line of the hull are slightly directed toward the centre line in the backwards direction of the vessel in order to increase the driving stability of the vessel. It is possible to allow the propulsion units to assume a slight "toe-out" position, that is the propulsion units on each side of the centre line of the hull are slightly directed away from the centre line in the backwards direction of the vessel. It is furthermore also possible to allow the propulsion units to assume an "Ackermann" position when taking curves, that is the outer unit is controlled to have a slightly less sharp turn than an inner unit in a turn, which increases the efficiency in curve taking. Furthermore efficient docking can be created by directing the propulsion units in opposing direction making the vessel to move sideward, and finally the trim position of the vessel can be adjusted by controlling the relative position of the propulsion units. Individual control over the position of the propulsion units is therefore even more desirable for small and middle size vessels since for this type of vessels a freedom to control trim angle and roll angle in curve taking is of far more concerns for small and middle size vessels than for large vessels. Small and middle size vessels however have a limited space for available for mounting of propulsion units. This is particularly true for highly powered small vessels crafted for planning speeds. A small vessel of less than 40 feet may have a contact area with the water as small as 10% of the contact area at standstill when driving at planning speed. The water contact area is located at a limited area close to the centre line at the stern of the vessel. All propulsion units must be positioned within the area of water contact. This means that, especially in the case where it is desired to mount a plurality of propulsion units on small boats very limited space is available.
It is desirable to provide an improved control system which enables use of a plurality of individually steered propulsion units in a small restricted area. The invention is useful, according at least to an aspect thereof, in cases where a plurality of propulsion units are mounted in a restricted area such that each propulsion unit is moveable within a working volume defined for each propulsion unit and wherein the working volume for neighbouring propulsion units of said at least two propulsion units have a common space. The working volume is the volume in space which may be occupied by a propulsion unit as is pivoted for steering purposes within an allowed angular range around the pivot axle. The range may be 360°, but is normally within a smaller interval of ±45° in relation to the centre line of the hull. In the event two propulsion units each have a working volume which share a common space there will be a risk for a collision between the exterior parts of respective propulsion unit if both propulsion units are steered such to be positioned within the common space. In order to avoid collisions the steering of each propulsion unit must be coordinated with the steering of neighbouring propulsion units. The invention ensures that such control is feasible.
The invention is based on a steering control system including at least two separate control units each controlling an associated propulsion unit, and a steering control instrument for determining the desired angular position of the propulsion units. The steering control instrument may preferably be constituted by a steering wheel or a joy stick.
Each of said separate control units are arranged for receiving a first input signal from said steering control instrument for determining the desired angular position of its associated propulsion unit and second input signal(s) originating from the other separate control units, which second input signal(s) indicating the status of the their associated propulsion units. It is here obvious that a single second input signal is needed in the event two propulsion units are installed in the vessel and that further second input signals may be necessary in the event more than two propulsion units. Generally the number of second input signals necessary for a separate control unit is equivalent to the number of neighbouring propulsion units a propulsion unit associated with the separate control unit. The notation input signal(s) is intended to be interpreted as input signal or input signals depending on whether a single or a plurality of input signals are received.
Each propulsion unit is moveable within a working volume defined for each propulsion unit and wherein the working volume for neighbouring propulsion units of said at least two propulsion units have a common space With neighbouring propulsion unit is here intended propulsion units which share a common space. In the event three propulsion units are positioned side by side, the two external propulsion units have each a single neighbour while the propulsion unit in the middle has two neighbours. If the propulsion units are positioned in a matrix with two in a front row and two in a back row, it may be possible that each propulsion unit has three neighbours.
In order to avoid collisions the steering system according to the invention each separate control unit in the system is arranged to admit its propulsion unit to be positioned within a first angular interval if said second input signal(s) indicates that the position of respective neighbouring propulsion unit is known and admit its propulsion unit to be positioned within a second more restricted angular interval if said second input signal(s) indicates that the position of respective neighbouring propulsion unit is not known.
The invention ensures that collision between the neighbouring propulsion units may be avoided even if information from the control units associated with neighbouring propulsion units is lost or becomes insecure. Different strategies and types of second input signals may exist.
In a least elaborate embodiment, the second input signal may only contain information indicating that the steering control of the associated propulsion unit does not malfunction. In this event a complete steering strategy stored in the control unit can be maintained allowing operation within a first angular interval partly or wholly encompassing the common space. In this event the steering strategy stored in each of the control unit does not use the position of the other propulsion units as an input variable but relies on that the other units are acting properly as was intended when developing the strategy. A propulsion unit may be allowed to enter the common space under certain circumstances. For instance if the vessel makes a turn and the outer propulsion unit may be allowed to enter the common space since the inner propulsion unit should have reach a position for from the common space unless the steering of the inner propulsion unit is malfunctioning. The knowledge of whether the steering control does not malfunction, which is an indication of that the position is known, would be sufficient. In the event an indication of that the position is not known is deducted from the second input signal, the propulsion unit should not be allowed to enter the common space.
Another strategy would to inform the neighbouring propulsion units of whether the neighbouring propulsion units are inside the common space or not. In the event the neighbouring propulsion unit is within the common space entry into the common space can be denied for further units. In the event second input signal(s) indicates that the position of respective neighbouring propulsion unit is not known the propulsion unit controlled by the control unit which has received said second input signal shall be denied from entry into the common space. The propulsion unit may therefore positioned within a second angular interval where the propulsion unit does not enter said common space of the neighbouring propulsion unit(s).
A further strategy would be to let the second input signal represent the angular position of the neighbouring units. In the event this information is transmitted to neighbouring units it is possible to allow two neighbouring propulsion units to enter into the common space simultaneously as long as the units are separated sufficiently from each other in order to avoid collision. The allowable range for a propulsion unit would then be dependent on the position of the neighbouring propulsion unit. In the event the second input signal(s) indicates that the position of respective neighbouring propulsion unit is not known, the propulsion unit receiving said second input signal may not enter the common space of the neighbouring propulsion unit concerned.
Examples of indications that the position of a neighbouring propulsion unit is not known are as follows:    1) The signal may be lost.    2) The signal has not been updated within a predetermined period of time or within a predetermined number of action sequences. This type of indication requires that the second signal carries information of the status of the associated propulsion unit, which information according to what has been stated above may be any one or a combination of (OK—not OK, propulsion unit position, inside or outside of the common space), and a time or sequence mark showing whether the signal is up-to-date or not.    3) The signal value is outside of an allowable range.
The invention furthermore relates to a vessel including a steering control system of the type referred to above.

Steering control system for a vessel, a vessel including such a steering control system and a method for controlling a steering system


It is a task of the present invention to provide a method for producing a high quality, high performance aromatic polycarbonate (which is colorless and has excellent mechanical properties) from a molten aromatic polycarbonate prepolymer obtained by reacting an aromatic dihydroxy compound with a diaryl carbonate, wherein the polycarbonate can be stably produced on a commercial scale at 1 to 50 t/hr for a long time. In the present invention, this task has been accomplished by a method for producing an aromatic polycarbonate by the melt transesterification process, in which the prepolymer is polymerized by a guide-wetting fall polymerizer device having a specific structure, whereby a high quality, high performance aromatic polycarbonate as mentioned above can be stably produced on a commercial scale at 1 to 50 t/hr for a long time (more than several thousand hours, e.g., more than 5,000 hours) without fluctuation of the molecular weight thereof.

In recent years, aromatic polycarbonates have been widely used in various fields as engineering plastics having excellent properties with respect to heat resistance, impact resistance, transparency and the like. With respect to methods for producing aromatic polycarbonates, various studies have heretofore been made. Of the methods studied, a process utilizing an interfacial polycondensation between an aromatic dihydroxy compound and phosgene (the so-called "phosgene process") has been commercialized, wherein 2,2-bis(4-hydroxyphenyl)propane (hereinafter, frequently referred to as "bisphenol A") can be mentioned as a representative example of the aromatic dihydroxy compound.
However, the interfacial polycondensation process has problems in that it is necessary to use phosgene, which is poisonous; that it is necessary to use a very large amount of methylene chloride as a polymerization solvent, which is considered to be harmful to human health and the environment, wherein methylene chloride is used in an amount which is ten times as large as the amount of the aromatic polycarbonate produced; that a reaction apparatus is likely to be corroded with chlorine-containing compounds, such as by-produced hydrogen chloride, by-produced sodium chloride, and methylene chloride used as a solvent; that difficulties are encountered in separating and removing chlorine-containing impurities (such as sodium chloride and residual methylene chloride), which adversely affect properties of the aromatic polycarbonate produced; and that it is necessary to handle a large amount of waste water containing methylene chloride and an unreacted aromatic dihydroxy compound (such as bisphenol A).
As a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate, a melt transesterification process has conventionally been known, in which an aromatic polycarbonate is produced by performing an ester exchange reaction between an aromatic dihydroxy compound (such as bisphenol A) and a diaryl carbonate (such as diphenyl carbonate) in the molten state, while removing an aromatic monohydroxy compound produced (such as phenol) from the equilibrium polycondensation reaction system. Contrary to the interfacial polycondensation process, the melt transesterification process has an advantage in that a solvent need not be used. However, the melt transesterification process has the following serious problem. The transesterification is an equilibrium reaction, and the equilibrium constant thereof is small. Therefore, the equilibrium reaction does not proceed unless the produced aromatic monohydroxy compound (such as phenol) is efficiently removed from the surface of a molten reaction mixture obtained by the transesterification. As the polymerization proceeds, the viscosity of a polymer being formed increases during the progress of the polymerization reaction and, hence, it becomes difficult to remove efficiently an aromatic monohydroxy compound (such as phenol) from the polymerization reaction system, thus making it difficult to achieve a high degree of polymerization with respect to a polycarbonate produced. That is, differing from the case of a melt polycondensation process for producing a polycondensation polymer (such as a polyamide or a polyester) other than an aromatic polycarbonate, the melt polycondensation process for producing an aromatic polycarbonate has the following problem. Even a prepolymer having a low degree (n) of polymerization (e.g., a prepolymer having an n value of from about 15 to about 20) has an extremely high melt viscosity and, hence, it is difficult to effectively facilitate the surface renewal of the prepolymer by usual agitation. Therefore, separation of an aromatic monohydroxy compound (such as phenol) from the surface of the polymerization reaction mixture does not occur, so that it becomes impossible to produce an aromatic polycarbonate having a high degree of polymerization (e.g., an n value of about 30 to about 65) which is required of an aromatic polycarbonate product for practical use. This problem is well known in the art.
Various polymerizers have been known for use in producing aromatic polycarbonates by the melt transesterification process. A vertical agitation type polymerizer equipped with an agitator is widely used for a small scale production in a laboratory. The vertical agitation type polymerizer equipped with an agitator is advantageous in that it exhibits high volumetric efficiency and has a simple construction, so that polymerization on a small scale can be efficiently carried out. However, when it is intended to use the vertical agitation type polymerizer for the production of an aromatic polycarbonate on a commercial scale, the following serious problem arises. When it is intended to use the vertical agitation type polymerizer for the commercial scale production of an aromatic polycarbonate, it is virtually impossible to effectively agitate the polymerization reaction mixture. Therefore, as mentioned above, it becomes difficult to efficiently remove an aromatic monohydroxy compound produced (such as phenol) from the polymerization reaction system, so that an aromatic polycarbonate having a desired degree of polymerization cannot be produced.
Specifically, a large-scale vertical agitation type polymerizer generally has a greater ratio of the liquid volume to the vaporization area than a small-scale one. In other words, the depth of a reaction mixture in the agitation type polymerizer is large and, hence, the pressure in the lower part of the agitation type polymerizer is high. In such a case, even if the degree of vacuum of the polymerization reaction zone is increased in order to achieve a high degree of polymerization, the polymerization proceeds under high pressure due to the weight of the reaction mixture in the lower part of the agitation type polymerizer, so that an aromatic monohydroxy compound (such as phenol) cannot be efficiently removed. Therefore, a large-scale vertical agitation type polymerizer is usable only in the production of a prepolymer having a low degree of polymerization. For obtaining a polymer having a desired degree of polymerization, it is necessary to subject the prepolymer having a low degree of polymerization obtained by using the agitation type polymerizer to a further polycondensation by using another polymerizer.
For solving the above-mentioned problem, various attempts have been made to remove an aromatic monohydroxy compound (such as phenol) from a high viscosity polymer being formed. Most of these attempts are concerned with improvement in mechanical agitation. For example, there are known a method using a screw type polymerizer device having a vent (see Examined Japanese Patent Application Publication No. Sho 50-19600 (corresponding to GB-1007302)); a method using an intermeshing twin-screw type extruder (see Examined Japanese Patent Application Publication No. Sho 52-36159); a method using a wiped film evaporation type reactor, such as a screw evaporator or a centrifugal film evaporator (see Examined Japanese Patent Application Publication No. Sho 53-5718 (corresponding to U.S. Pat. No. 3,888,826)); and a method using a combination of a wiped film evaporation type apparatus and a horizontal agitation type polymerizer (see Unexamined Japanese Patent Application Laid-Open Specification No. Hei 2-153923).
However, each of the above-mentioned methods mainly uses the technique of mechanical agitation and, hence, inevitably has a limitation accompanying the technique, so that it is impossible to completely solve the above-mentioned problem. Specifically, it is difficult to satisfactorily agitate a polymer having an extremely high viscosity by mechanical agitation and, hence, various problems encountered in the production of an aromatic polycarbonate from a prepolymer having an extremely high viscosity cannot be solved. On this point, a detailed explanation is given below.
In the above-mentioned method, it is attempted to lower the melt viscosity of the prepolymer as much as possible by elevating the temperature of the prepolymer. Specifically, the polymerization of the prepolymer is performed at a high temperature which is close to 300° C. under high vacuum while mechanically agitating the prepolymer so as to effect the surface renewal of the prepolymer. However, even at such a high temperature, the melt viscosity of the prepolymer is still very high, so that it is impossible to satisfactorily effect the surface renewal of the prepolymer. Therefore, by this method, the increase in the polymerization degree of the aromatic polycarbonate is inevitably limited and, hence, it is impossible to obtain a high molecular weight aromatic polycarbonate. Further, the method has the following disadvantage. Since the method is practiced at a high temperature which is close to 300° C., it is likely that the polymer produced suffers discoloration and lowering of properties. Further, it is likely that discoloration and lowering of properties of the polymer are also caused due to entrance of air and foreign matter into the polymerizer device through the vacuum-sealed gap between the casing of the polymerizer device and the rotary axis. Therefore, when it is intended to stably produce, by the method, a high quality aromatic polycarbonate for a long period of time, it is still necessary to solve various problems.
The present inventors completely solved the above-mentioned problems by developing methods which do not involve mechanical agitation. Specifically, the present inventors developed methods using a guide-wetting fall polymerizer device in which a molten prepolymer is allowed to fall along and in contact with the surface of a guide, such as a wire, thereby effecting polymerization of the molten prepolymer to produce a desired polymer (see Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-225641, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-225643, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-325373, W097/22650, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 10-81741, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 10-298279, WO99/36457, and W099/64492).
However, none of the above-mentioned patent documents has any teaching or suggestion about a method for producing an aromatic polycarbonate on a commercial scale at a rate of 1 t/hr or more. Further, it has been found that, even when the relatively small scale polymerizer devices disclosed in the above-mentioned patent documents are used for producing an aromatic polycarbonate for a long period of time, it is possible that the resultant aromatic polycarbonate product sometimes contain a very small amount of a polymer mass having too high a molecular weight, which generally has a size of 1 mm or less. Therefore, it has been desired to provide a method for stably producing a very high quality aromatic polycarbonate on a commercial scale at a rate of 1 t/hr or more for a long period of several thousand hours or more (for example, a period of time as long as 5,000 hours or more).

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Method for producing an aromatic polycarbonate