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National Aerospace and Electronics Conference, 2000. NAECON 2000. Proceedings of the IEEE 2000

Date 12-12 Oct. 2000

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Displaying Results 1 - 25 of 112
  • National Aerospace and Electronics Conference NAECON 2000 [front matter]

    Publication Year: 2000 , Page(s): 0_1 - xi
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    Freely Available from IEEE
  • Primary Authors

    Publication Year: 2000 , Page(s): 814 - 816
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    Freely Available from IEEE
  • Low temperature processed lead zirconate titanate (PZT) film as dielectric for capacitor applications

    Publication Year: 2000 , Page(s): 560 - 567
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    Thin PZT film is being developed for use in microelectronics, electromechanical and optoelectronic applications. Thin Pb(ZrTi)O3 film capacitor devices were fabricated using RF sputtering techniques. The multiple-layer configuration of Si/SiO2/Ti/Pt was used as the substrate and bottom electrode. The top electrode was Pt. At 1 kHz, the dissipation factor (tangent loss) of PZT film capacitors processed at 100°C was 8.35%. However the dissipation factor of PZT film capacitor processed at 60°C was only 0.35%. The dielectric constant was calculated to be 32 at 1 kHz. After annealing at 400°C, the dielectric constant increased about 33% to 43. The dielectric constant increased to 165 after annealing at 500°C and to 1143 after annealing at 600°C. The PZT film capacitors produced to-date had little dependence on frequency from 20 Hz to 100 kHz. The frequency dependence increased with increasing annealing temperature from 400°C to 600°C. Lowering the processing temperature from 100°C to 60°C resulted in a tremendous decrease in the dissipation factor from 8.3% to 0.35% View full abstract»

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  • Wide-angle scanning with reflector antennas: a new design technique

    Publication Year: 2000 , Page(s): 136 - 145
    Cited by:  Papers (3)  |  Patents (1)
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    Some applications, such as space-based radar, require wide-angle scanning and very narrow beamwidths. Hybrid antennas, which are reflector antennas fed by arrays, may provide an alternative to the use of large array antennas in these applications. This paper presents a numerical method for shaping the reflector to maximize the collected energy over the desired scan range. By experimenting with various feed array sizes and shapes, and using the methods presented herein to find the optimal reflector shape at each step, one may arrive at designs that minimize the feed array surface area while meeting various system design objectives such as scan range, aperture size, and aperture utilization. Optimization examples are provided for several feed array configurations, along with analyses of the resulting performance over the desired scan range View full abstract»

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  • The primary research on image color quality evaluation

    Publication Year: 2000 , Page(s): 201 - 207
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The image color and vision quality evaluation plays a very important role in the algorithm design and their optimizations of image reconstruction processing. As human eyes are the last receivers for image information, we build a general evaluation model on the HVS (human visual system) and HCPM (human color perception model). According to the psychology and physiology experiments and color perception tests, by which “representation without reconstruction” is the precondition of visual perception, we build a bottom-up information acquisition model under top-bottom feedback processing driven by knowledge. In the model, the visual information from different position with varied spatial resolution is dealt with the quantificational and qualitative analysis under the precondition of the guidance of the given task and well perceptional condition View full abstract»

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  • A DSP-based indirect field oriented induction machine control by using chattering-free sliding mode

    Publication Year: 2000 , Page(s): 568 - 573
    Cited by:  Papers (2)
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    This paper has attempted to improve the speed control performance of an indirect field oriented (IFO) induction motor drive system by using a continuous sliding mode controller. The proposed continuous sliding mode controller is robust to load changes and system disturbances which are unique features of discontinuous sliding mode control. Also it is free from chattering which is the main problem of discontinuous sliding mode control. The proposed controller can also overcome the performance degradation and avoid tedious tuning process associated with the PI controller. The results of PI and sliding mode controller (SMC) are compared through extensive simulation and experimental work. These results prove that the proposed controller is robust to load changes and system disturbances and can also follow different command trajectories very well without re-tuning of the controller View full abstract»

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  • Design of a reconfigurable automated landing system for VTOL unmanned air vehicles

    Publication Year: 2000 , Page(s): 801 - 806
    Cited by:  Papers (3)
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    With the release of Bombardier's redesigned vertical take-off and landing unmanned air vehicle (VTOL UAV), the company's development team was interested in exploring fresh avenues for automatically landing the craft. The focus of this redesign revolved around navigation via DGPS data. The development of three principle components were identified as being paramount to the success of the system. First was the need for an algorithm to locate an appropriate intercept point on the intended landing profile. Landing initiated the switch of navigation modes from one using GPS to one employing DGPS. This differing of sources and their respective accuracies led to position errors between expected and actual craft location, thereby necessitating the inclusion of the flight-path intercept algorithm. With the establishment of concrete target points, a corroborative effort was required between the second and third components of the autoland system to provide motion control between two arbitrary points in space. The first of the two, a trajectory generator, provides an ideal locus of points based on a time law, paying careful attention to the craft's acceleration. A controller using the ideal points generated by the trajectory generator drives the craft and was the second component of the motion control system. The controller configuration was kept simple, due in no small part to the project's scope. The initial evaluation tool for theory development was a simplified version of Bombardier's overall craft dynamics model for the CL-327. This was then followed by tests with a high-fidelity model. Currently, flight testing is in progress View full abstract»

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  • Concurrent engineering: evolution and application

    Publication Year: 2000 , Page(s): 737 - 744
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    When a new complex electronic product is being developed, an approach is chosen, either directly or indirectly, to obtain the final design. Once the approach is chosen or implied, it is followed throughout the design and development phase. This is done to ensure that it will meet the specified requirements within the mechanical, electrical, and other environmental constraints. One approach allows all ingredients crucial of a successful product to be considered, such as: design, manufacturing, testing, reliability, human factors, producibility, and cost, as well as customer's needs and satisfaction. This approach-Concurrent Engineering-can be defined as a systematic team approach in which all disciplines participate in the design and development of products and related processes simultaneously to obtain common objectives. This paper delineates the detailed processes and procedures to implement concurrent engineering effectively and makes specific recommendations to obtain the desired results. In the process, it compares concurrent engineering to a symphony orchestra to illustrate the profit to be realized when all of the involved disciplines cooperate to produce the final product View full abstract»

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  • Tuning of fuzzy logic controller using neural network

    Publication Year: 2000 , Page(s): 305 - 312
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    The transformation of expert's knowledge to control rules in a fuzzy logic controller has not been formalized and arbitrary choices concerning, for example, the shape of membership functions have to be made. The quality of a fuzzy controller can be drastically affected by the choice of membership functions. Thus, methods for tuning fuzzy logic controllers are needed. In this paper, neural networks and fuzzy logic are combined to solve the problem of tuning fuzzy logic controllers. The neuro-fuzzy controller uses the neural network learning techniques to tune the membership functions while keeping the semantics of the fuzzy logic controller intact. Both the architecture and the tuning algorithm are presented for a general neuro-fuzzy controller. From this, a procedure to tune a proportional fuzzy controller is obtained. The algorithm for off-line tuning of the fuzzy controller is demonstrated with a numerical example View full abstract»

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  • New millennium ultralow power microsystems

    Publication Year: 2000 , Page(s): 459 - 468
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    Mixed-signal electronics form the core of spacecraft avionics systems. Low-power operation is a key design objective to reduce dependence on stored energy or energy extraction systems. To facilitate low-power operation. The supply voltage of mixed-signal systems has progressively diminished to typical present values of 3.5 V to 3.6 V. Low voltage design, however, increases susceptibility to noise interference and reduces the range of analog linear gain. Moreover, as transistor density and circuit complexity increase, traditional power minimization methods are inadequate. In this paper we present results of several approaches to enable low-power mixed-signal electronics for spacecraft avionics and commercial telecommunications. First, at the architectural level we analyze a dynamic voltage scaling approach that delivers local isolation of bus noise and a power reduction of 50% to 95%. Next, to enable in-situ, real-time power sensing we introduce two sensors that monitor di/dt and dv/dt events. Their design, scaling, and sensitivity are discussed in detail. Finally, as an example of a low-voltage compatible analog circuit we present results of a low-noise differential analog-to-digital comparator. It operates at speeds to over 50 MHz, has per-comparator power dissipation under 1 mW, and can operate at supply voltages down to 1.9 V. All circuits have been designed and analyzed for a 0.5-μm CMOS, and analytical and experimental results are given View full abstract»

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  • Work-centered Support System technology: a new interface client technology for the battlespace infosphere

    Publication Year: 2000 , Page(s): 499 - 506
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    Information superiority is a strategic goal of the US Air Force. To achieve this goal the Air Force aims to produce a battlespace infosphere that will provide an unprecedented degree of connectivity and availability of raw data and value-added information for warfighter use. The essential challenge of the infosphere is to be able to provide the right information, at the right time, in the right form to enable warfighters to take effective, coordinated action. Although the infosphere's core web and agent technologies are clearly able to provide a heterogeneous infosphere, improved interface technologies are also needed to address problems of information overload and how to provide support to specific end-users without the support tools themselves becoming an impediment to task performance. We have developed a prototype Work-Centered Support System software client as a means to address these interface issues. The WCSS approach achieves effective support in a software agent environment by blending direct manipulation work field organization, and decision, collaborative, and product development aiding in a manner that is tailored to both formal and informal characteristics of user work. In this paper we describe the philosophy behind and characteristics of the WCSS technology. We illustrate the technology with a discussion of an interactive WCSS prototype designed to improve support to military airlift mission planners at the headquarter level View full abstract»

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  • A new sliding mode flux and speed observer for speed sensorless control of induction machine

    Publication Year: 2000 , Page(s): 574 - 578
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    In this paper a new sliding mode flux and speed observer is proposed for induction machine drive systems. The error between the actual and observed currents converges to zero which guarantees the accuracy of the flux observer. The rotor speed and the rotor time constant are estimated based on the estimated stator currents and rotor flux. The estimated rotor time constant is used in slip calculation and observer structures and the estimated speed is used as feedback to the speed regulation. Computer simulation results of the speed control verify the validity of the proposed speed estimation algorithm View full abstract»

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  • Model based cost optimization for engineering and management

    Publication Year: 2000 , Page(s): 745 - 752
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    Long lasting systems like airplanes have a cost structure where the maintenance costs are larger than the purchasing costs. Besides, the growing amount of electronics leads to a much higher sensitivity with respects of failures in the electronic system. Testing is required, both for preventive maintenance as well as repair. Previously we have looked at the impact of test and design for testability on the cost structure. We have developed a complex cost model as well as a state of the art of cost modeling tool that allows the evaluation of the model. Finally, we show how cost modeling can effectively be integrated into the system design flow View full abstract»

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  • Remote control structural exciters for structural data acquisition system calibrations

    Publication Year: 2000 , Page(s): 95 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB)  

    The Air Force invented a new calibration technique, which allows one person to perform multiple end-to-end mechanical calibrations of structural dynamics measurement systems. An end-to-end calibration means a full calibration of instrumentation from the physical input to the transducer to the output where the analog or digital signal is normally analyzed. It is difficult to stimulate mounted and embedded transducers with known physical inputs. Normally two people calibrate-one at the transducer holds or attaches the exciter and one operates the recorder. This new technique uses remote control structural exciters to stimulate measurement transducers contained in structures, with a measurable input level, and the output signal is communicated to a data recorder. The Air Force demonstrated this patented technique by using accelerometers in the laboratory. A commercial off-the-shelf vibration paging system sends a signal from a master control unit to individual exciters that stimulate accelerometers mounted on structures. A reference accelerometer measures the input. Engineers validated the technique using eight different exciters in a completely randomized block design experiment consisting of three 2-level factors: material, structural thickness and excitation mode. The engineers measured amplitude, frequency and transfer function between the accelerometers. This paper describes the invention and looks at potential field applications to insure data integrity in structural data acquisition systems on aging commercial and military vehicles View full abstract»

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  • Comparing performance of static versus mobile multiagent systems

    Publication Year: 2000 , Page(s): 282 - 289
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    This paper analyzes the performance differences between static and mobile multiagent systems. To do so, we developed solutions to a distributed text search problem, each using a different approach to multiagent systems (static versus mobile) on an isolated test network. Changes were then made to the agent environment, various constraints applied, and the resulting effect on the systems measured. Each system was evaluated using a number of performance metrics to demonstrate the strengths and weaknesses of the respective approach View full abstract»

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  • Agent-based architecture for modeling and simulation integration

    Publication Year: 2000 , Page(s): 375 - 382
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The Department of Defense (DOD) has an extensive family of models used to digitally simulate the mission level interactions of weapon systems. Interoperability and reuse of the underlying data files used to create simulation scenarios are of particular interest to the modeling community. We develop an architecture to support simulation interoperability by combining three key technologies: object-oriented data modeling, an underlying persistence mechanism, and an agent-oriented analysis and design methodology. We use object-oriented modeling techniques to encapsulate and organize the syntactic information contained in scenario database files while we examine the semantic information of these objects for data integration purposes. The agent architecture provides a communication capability to support collaborative development and information brokering. We demonstrate our architecture by means of prototypical applications that implement the foundational information agent layer View full abstract»

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  • Implementation of roll motion in magnetic suspension wind tunnel

    Publication Year: 2000 , Page(s): 758 - 765
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    Wind tunnel tests are generally obstructed by model support with limitations. The development of magnetic suspension wind tunnel (MSWT) is designed to free the model from conventional mechanical supports. Under precise model design, a roll motion with appropriate control can be implemented in MSWT. This paper presents a modification of NCKU 10 cm×10 cm MSWT to accomplish the roll motion control in wind tunnel tests. The modification of this experiment includes position and attitude sensing and test model design. The position and attitude sensing is improved and set-up by a laser-optical circuit, quadrant detectors and dual-lateral detector in x-axis to ensure accurate measure. The rolling inertia is generated from a rotating mass inside the test model. With very careful design, a rocket model is fabricated for experiments. A passive PID control is implemented to achieve the predictable constant roll motion on the test model. A current feedback loop is applied to strengthen the control stability. Being different from other MSWT applications, the test model is locked by the position and attitude sensing via feedback control loop. Due to the accomplishment of motion test roll only constant speed in good control limitations, demonstrates performance. The idea of this study is to extend dynamic test capability in the magnetic suspension wind tunnel, and bring further valuable applications View full abstract»

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  • Dynamic modeling and optimal control of a twin rotor MIMO system

    Publication Year: 2000 , Page(s): 391 - 398
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    A dynamic model for the characterising of a one-degree-of-freedom (DOF) twin rotor MIMO system (TRMS) in hover is extracted using a black-box system identification technique. The behaviour of the TRMS in certain aspects resembles that of a helicopter. Hence, it is an interesting identification and control problem. Identification for a 1-DOF rigid-body, discrete-time linear model is presented. The extracted model is employed in the design of a feedback LQG compensator. This has a good tracking capability, but requires high control effort and has inadequate authority over residual vibration of the system. These problems are resolved by further augmenting the system with a command path prefilter. The combined feedforward and feedback compensator satisfies the performance objectives and obeys the actuator constraint View full abstract»

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  • Nonlinear modelling of a twin rotor MIMO system using radial basis function networks

    Publication Year: 2000 , Page(s): 313 - 320
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    Modelling of innovative aircraft such as UAVs, X-wing, tilt body and delta-wing is not easy. This paper presents a nonlinear system identification method for modelling air vehicles of complex configuration. This approach is demonstrated through a laboratory helicopter. Extensive time and frequency-domain model-validation tests are employed to instil confidence in the estimated model. The estimated model has a good predictive capability and can be utilized for nonlinear flight simulation studies. The approach presented is suitable for modelling new generation air vehicles View full abstract»

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  • Extending the notation of Rational Rose 98 for use with formal methods

    Publication Year: 2000 , Page(s): 43 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    The Unified Modeling Language (UML) has been incorporated into the CASE tool, Rational Rose98, offering the user the capability of specifying systems using UML notation, Booch notation, or Rumbaugh notation. Through this research effort, Rose98 has been extended to allow formal notation to be entered in the class diagram text fields. Rose scripts were developed to transform the resulting extended Rose model into Z (zed) specifications in LATEX format. Z specifications are developed for the object model, dynamic model, and functional model based on information gathered from the class diagram and state transition diagram of the Rose model. These specifications can then be parsed into a tool supporting formal methods and Ada code can be automatically generated View full abstract»

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  • An optimal bandwidth allocation scheme and real-time performance analysis for LTPB network

    Publication Year: 2000 , Page(s): 180 - 186
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    This paper studies the problem of guaranteeing real-time message deadlines in communication networks where the LTPB protocol, Linear Token Passing Bus, is employed. According to the exact network timing property, an optimal bandwidth allocation scheme (OLA) for LTPB network and a real-time performance analysis method based on WCAU (the worst available utilization) are proposed. Formal proof that OLA has better performance than any other schemes is given. Finally examples are given to demonstrate the correctness of the conclusion View full abstract»

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  • Assessing system performance using component level performance specifications

    Publication Year: 2000 , Page(s): 469 - 475
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Performance of software components may be characterized in a way that permits software architects to predict response times that result after integrating multiple components. Using information about individual component execution time and invocation rates, this method predicts processor utilization and “thread” latency (where a thread is an executed string of components). The method derives component budgets which can be individually verified via empirical tests and which assure system response times meet specified requirements. In the event budgets do not support satisfactory system response times, the method determines what components should be optimized in order to produce the desired system result. When calculating budgets or when identifying optimization goals for components, the method considers difficulty of component optimization. The method is based on a simple application of mathematical concepts from queuing theory and optimization theory and may be implemented using a spreadsheet. This method was used to develop component based budgets for a large complex software intensive system View full abstract»

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  • Predicate ranking algorithms and their application in an inductive logic programming system

    Publication Year: 2000 , Page(s): 51 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Inductive logic programming (ILP) is a form of machine learning that induces rules from data using the language and syntax of logic programming. A rule construction algorithm forms rules that summarize data sets. These rules can be used in a large spectrum of data mining activities. In ILP, the rules are constructed with a target predicate as the consequent, or head, of the rule, and with high-ranking literals forming the antecedent, or body, of the rule. The predicate rankings are obtained by applying predicate ranking algorithms to a domain (background) knowledge base. We present three new predicate ranking algorithms for the inductive logic programming system, INDED (pronounced “indeed”). The algorithms use a grouping technique employing basic set theoretic operations to generate the rankings. We also present results of applying the ranking algorithms to several problem domains, some of which are universal like the classical genealogy problem and others, not so common. In particular, diagnosis is the main thread of many of our experiments. Here, although our experimentation relates to medical diagnosis in diabetes and Lyme disease, many of the same techniques and methodologies can be applied to other forms of diagnosis including system failure, sensor detection, and trouble-shooting View full abstract»

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  • Updating the focusing matrix for the DOA estimation of moving sources

    Publication Year: 2000 , Page(s): 723 - 727
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    In this paper, a new method is proposed for tracking the direction-of-arrival (DOA) of the wideband moving source incident on uniform linear array sensors. DOA is estimated by focusing transformation matrices. To update focusing matrices along with new data snap shots, we use the FAST (fast approximate subspace tracking) method. Present focusing matrices are constructed by previous signal and its orthogonal basis vectors as well as present signal and its orthogonal basis vectors, which are the left and right singular vectors of the inner product of two approximated matrices. Simulation results are shown to illustrate the performance of the proposed method View full abstract»

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  • A novel approach of rotor position detection for PM machines based on conventional PWM algorithms

    Publication Year: 2000 , Page(s): 547 - 553
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Based on conventional PWM modulation techniques and low inductance characteristics of PM machines, this paper presents a novel and practical approach of rotor position estimation for a PM machine. In conventional PWM modulations such as sin-Δ and Space Vector PWM techniques, there are three voltage vectors in action during each sampling period. For each different voltage vector, the phase current change will be different. By measuring the current changes under different voltage vectors, the back-EMF can be obtained and therefore the rotor position estimated. In this method, no prior knowledge of the machine parameters is needed. Further, at low speed, the back-EMF detection technique works well because the current ripples at very low speed are effectively utilized and no integration is needed. The proposed approach has been investigated by comprehensive computer simulation and the experimental testing results illustrate the effectiveness of the proposed approach View full abstract»

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